bei       'lade  by  Nature's 
i  Tot  Artisans. 


Drawn  by  A   H.Sadtlt 


-  CHEMISTRY  OF 
FAMILIAR  THINGS 


BY 

SAMUEL  SCHMUCKER  SADTLER,  S.B. 

MEMBER  OF  THE  AMERICAN  INSTITUTE  OF   CHEMICAL  ENGINEERS,   THE  AMERICAN  CHEM- 
ICAL SOCIETY — FORMER   SECRETARY   AND   VICE-PRESIDENT    OF    THE   AMERICAN 
ELECTROCHEMICAL    SOCIETY,    MEMBER    OF    THE    SOCIETY    OF    CHEMICAL 
INDUSTRY,  THE  AMERICAN  SOCIETY  FOR  TESTING  MATERIALS,  THE 
AMERICAN    PUBLIC    HEALTH    SOCIETY,    ETC. — AMERICAN 

EDITOR  "Allen's  Commercial  Organic  Chemistry" 


PHILADELPHIA  AND  LONDON 
J.  B.  LIPPINCOTT  COMPANY 


COPYRIGHT,  191 S 
BY  J.  B.  LIPPINCOTT  COMPANY 


PRINTED    BY  J.  B.  LIPPINCOTT  COMPANY 

AT  THE  WASHINGTON  SQUARE  PRESS 

PHILADELPHIA,  U.  S.  A. 


TO  MY  WIFE 


PREFACE 

THIS  book  has  been  written  because  of  a  demand  for 
an  insight  into  chemistry  by  those  whose  training  or 
whose  reading  has  been  directed  in  other  channels. 
Chemistry  has  been  regarded  as  a  difficult  and  con- 
fusing study  by  beginners ;  yet  they  seem  to  grant  that 
it  must  be  a  very  absorbing  and  interesting  pur- 
suit to  the  chemist  himself.  If  this  be  true  it  is  only 
necessary  for  the  chemist  to  present  the  subject  with  its 
natural  attractions  in  a  non-technical  way.  He  may 
then  both  instruct  and  interest  those  who  would  like  to 
extend  their  courses  of  reading  to  learn  more  about 
natural  phenomena  and  to  familiarize  themselves  with 
things  in  Nature  and  the  Arts. 

The  writer  has  dwelt  at  some  length  upon  the 
chemistry  of  such  subjects  as  Air,  Water,  Metals,  Bocks, 
Soil,  Food,  Textiles,  Chemical  Evolution  and  Physio- 
logical Chemistry,  and  has  only  introduced  enough 
elementary  chemistry  in  the  first  chapter  to  enable  the 
reader  to  understand  and  appreciate  the  sequel. 

The  writer  offers  this  book  for  perusal  by  those  who 
are  interested  in  scientific  matters  and  for  careful  study 
by  those  who  desire  an  exposition  of  every-day  prac- 
tical chemistry.  It  is  probable  that  short  courses  in 


vi  PREFACE 

chemistry  can  render  more  concrete  results  and  be  more 
productive  of  real  benefit  by  the  use  of  such  a  book  as 
this  rather  than  a  text-book  of  the  more  usual  kind. 

The  author  wishes  hereby  to  acknowledge  his  in- 
debtedness to  Dr.  S.  P.  Sadtler  and  Mr.  C.  0.  Bond  for 
suggestions  made  use  of  in  the  manuscript  and  proofs 
and  to  his  sister,  Alice  H.  Sadtler,  for  her  interest  in 
making  original  sketches  for  illustrations.  For  kind- 
ness in  furnishing  photographs  for  illustrations  Prof. 
Albert  Sauveur,  Dr.  E.  F.  Eoeber,  Prof.  Louis  V. 
Pirsson,  The  Lowell  Observatory  and  the  Eesearch 
Corporation  are  also  thanked  by  the  writer. 

CHESTNUT  HILL,  PHILADELPHIA  S-  S' 

October  5, 1914. 


CONTENTS 

INTRODUCTION 

PAGE 

Chemical  Substances  Formed  by  Insects 2 

Chemical  Substances  from  Plants 4 

Exact  Knowledge  of  the  Composition  of  Matter  Desirable 6 

CHAPTER  I— BRIEF  CHEMICAL  OUTLINE 

Place  of  Chemistry 7 

Elements 8 

Atoms  and  Molecules 9 

Acids  and  Bases  (Alkalies) 11 

Use  of  Indicators 12 

Inorganic  and  Organic  Substances 14 

Oxidation  and  Reduction 16 

CHAPTER  II — HISTORICAL  DEVELOPMENT  OF  CHEMISTRY 

Alchemy 20 

Indestructibility  of  Matter 23 

Discoveries  of  Elements 24 

Combination  in  Definite  Proportions 25 

CHAPTER  III— THE  PERIODIC  SYSTEM  OF  ELEMENTS 

Relationship  of  Groups  of  Elements 28 

Periodic  Table opposite  30 

CHAPTER  IV — THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT 

Cause  of  Blue  in  Sky 32 

Complementary  Colors 34 

Artificial  Daylight 35 

Phosphorescence 36 

Effect  of  Light  on  Substances 37 

Efficiencies  of  Lights 38 

Illuminating  Gas 40 

Products  from  Petroleum 42 

Tungsten  Lamps 44 

Electricity  from  Batteries 46 

Volts  and  Amperes 47 

Gas  Mantles  and  Matches 49 

vii 


viii  CONTENTS 

CHAPTER  V — HEAT,  COMBUSTION,  AND  INSULATION 

,  KTemperature 54 

^Sources  of  Heat 55 

Heat  in  Houses 57 

Latent  Heat , 60 

Insulation 60 

Coalettes '. . . : 63 

CHAPTER  VI — Am,  OXIDATION,  AND  VENTILATION 

Atmospheric  Pressure 65 

Composition  of  the  Air 68 

Humidity 70 

Ozone 71 

Nebular  Hypothesis 73 

Ventilation 74 

Ozonation  of  the  Air 80 

CHAPTER  VII— WATER 

Chemically  Combined  and  Physically  Held  Water 82 

Composition  of  Pure  Water 83  ' 

Some  Properties  of  Water 84 

Solids  in  Natural  Waters 87 

Chemists'  Reports  on  Water 87 

Counting  Bacteria 89 

Hard  Waters 91 

Softening  Water 92 

^/Purifying  Water 93 

Sea  Water 96 

\ 
CHAPTER  VIII— ALKALIES  AND  SALTS 

Lithium  Salts 98 

Sodium  Compounds 99 

Potassium  Salts 103 

Ammonium  Compounds 104 

Artificially-made  Compounds  of  Nitrogen 106 

Calcium  Compounds 107 

Barium  Compounds 108 

Magnesium  Compounds 110 

Halogens 110 

Sulphur Ill 

Borax , .  112 


CONTENTS  ix 

CHAPTER  IX— METALS 

vOres  of  Metals 113 

Fume  Precipitation  by  Cottrell  Process 114 

Iron 115 

Micro-structure  of  Steel 118 

Rusting  of  Iron  and  Steel 119 

Aluminum 122-* 

Zinc 124 

Copper 126 

Lead,  etc 128 

CHAPTER  X— GOLD  AND  SILVER 

Silver 133 

^  Cleaning  Silver  Electrolytically 135 

Photographic  Processes 137 

Gold 138 

Radium 140 

CHAPTER  XI — CHEMISTRY  OF  THE  EARTH'S  EVOLUTION 

Earth  as  it  Condensed  from  the  Gaseous  State 144 

Tearing-down  Agencies 147 

Composition  of  Ocean  and  River  Waters 149 

Building-up  Processes 151 

Formation  of  Coal,  etc 156*. 

CHAPTER  XII— SOIL  AND  ITS  CONSERVATION 

Burroughs  on  Soil  Formation 158 

Agencies  of  Soil  Formation 159 

Essentials  of  Soil 162 

Mineral  Substances  hi  Soil 164 

Capillarity  of  the  Soil 167 

Plant  Foods 168 

Bacteria  in  Soil 172 

Cycle  of  Nitrogen  hi  Soil 174 

CHAPTER  XIII — FOOD  ELEMENTS  AND  FOOD  CLASSES 

Function  of  Food 17^ 

Body  Enzymes 179 

Digestion  of  Foods 181 

Ratio  of  Food  Elements 182- 

Calories  Required 185 


x  CONTENTS 

Work  Done  by  Food  Energy 188 

Cooking  of  Foods 189 

Pure  Foods 191  - 

Effects  of  Alcohol. 194 

CHAPTER  XIV— INDIVIDUAL  FOODS 

Oysters 196 

Fish 197 

Eggs  and  Milk 198 

Prepared  Milks 202 

Oleo  and  Oils 204 

Cheese 205 

Meat 206 

Sausage 209 

Vegetable  Foods 210 

Flours 213 

Baking  Powders 214 

Fruits 217 

Nuts 219 

Qp  Syrups 221 

Tea,  Coffee,  and  Cocoa 222 

CHAPTER  XV— ANIMAL  FEEDING 

Composition  of  Feeding  Stuffs 225 

Animal  Internal  Combustion  Engine 226 

Food  for  Maintenance  and  Work 227 

CHAPTER  XVI— FERMENTATION 

Alcohol  Formation 230 

^Sugars 231 

Yeast 231" 

Bread-making 232 

Cider 234 

Beer 235 

Wine 237 

Ardent  Spirits 240 

Alcohol 241 

CHAPTER  XVII— CHEMISTRY  OF  THE  BODY 

Enzyme  Action 244 

Chemistry  of  Parts  of  Body. . . : 246 


CONTENTS  xi 

Blood 247 

Teeth 249 

Effect  of  Sunlight 252 

Water 254 

Antiseptics 255 

Sewage  Disposal 257 

Poisons..,  259 


CHAPTER  XVIII — SOAPS,  SOLVENTS,  AND  PAINTS 

/  Soap 

Hardened  Fats 264 

Laundry  Soaps,  etc — 266 

Solvents 267 

Oils 268 

Stains  and  Varnishes 270 

Paint  Removers. .  .  271 


CHAPTER  XIX— PAPEB  AND  TEXTILES 

XCellulose. 273 

'    Materials  Used  to  Make  Paper 275 

Paper-making 276 

^Celluloid. 280 

Tests  for  Kinds  of  Fibres 281 

Cotton 282 

Wool 283 

Silk 285 

Artificial  Silk. .  ...  285 


CHAPTER  XX — LEATHER  AND  RUBBER 

Hide  Structure 287 

Chrome  Leather 290 

Patent  Leather 291 

Care  of  Leather 292 

Rubber 293 

Resins  in  Rubber 294 

Synthetic  Rubber 294 

Vulcanization  of  Rubber 295 

Automobile  Tires 296 

Care  of  Rubber'. 298 

Cements. 299 


arii  CONTENTS 

CHAPTER  XXI — SILICIOUS  SUBSTANCES  AND  GLASS 

Silica  and  Pure  Silica  Ware 300^" 

7*  Silicates 301 

Rocks. 302 

Building  Stones 305 

Road  Stones 306 

How  to  Distinguish  Ordinary  Rocks 306 

*Glass  Making 307  " 

j,  Colors  in  Glass 308 

Earthenware 309 

^Porcelain 309 

Precious  Stones. 310 

^  Portland  Cement 311 

Asbestos 312 

CHAPTER  XXII— A  FEW  IMPORTANT  DEFINITIONS 

ft  Catalytic  Agents 314 

Enzyme  Action 314 

Colloid  Chemistry 315 

Eutectic  Alloys* 315 

Petrography.. 315 

Radio-activity 316 

Synthetic  Chemistry 316 

INDEX 317 


ILLUSTRATIONS 

PLATES 

PAGE 

Chemical  Products  being  made   by   Nature's   Insect   Arti- 
sans-.   Frontispiece 

I.  Metal  Growths  from -Solutions 19 

II.  Early  Chemical  Laboratory 22 

III.  Phosphorescence  in  Water 36 

IV.  Petrified  Tree  Stump  in  Coal  Vein 56 

y  fElectric  Ozonizer \  _  gg 

'  \Petri  Dishes  with  Water  Bacteria/ ' 

VI.  Effects  due  to  Lime  Deposits  in  Luray  Cave '. 92 

VII.  Views  of  Rescue  Helmet 104 

yjjj  (Tumping  Sulphur  hi  Louisiana!  .112 

'  \Rotary  Cement  Furnace J 

IX.  Precipitation  of  Fume  Dust  by  Electricity 114 

X.  Heroult  Electric  Steel  Furnace 116 

XL  Photomicrography  of  Steel. , 118 

XII.  Photomicrography  of  Steel  and  Iron 120 

XIII  /Electrolytic  Cleaning  of  Silver!  14Q 

IRadiographs / 

XIV.  Rings  of  Saturn 144 

XV.  Effects  of  Erosion 148 

XVI.  Columnar  Structure  in  Lava 150 

XVII.  Buttes  of  the  Green  River 158 

XVIII.  Alfalfa  Plants  with  Root  Nodules 174 

XIX.  Human  Calorimeter 178 

XX.  Model  Dairy  Farm 200 

XXI .(Familiar  Varieties  of  Starch!  220 

iMould  Plants j" 

XXII.  Paper  Machine 278 

XXIII.  Rock  Sections 302 

FIGURES  IN  THE  TEXT 

1.  Solar  Spectrum 33 

2.  Mercury  Barometer 66 

3.  Electric  Air  Ozonator 80 

4.  Ultra-violet  Water  Sterilizer 94 

5.  Effect  of  Temperature  on  Different  Ferments 233 

6.  Section  of  Hide 288 

xiii 


CHEMISTRY 
OF  FAMILIAR  THINGS 

INTRODUCTION 

CHEMISTRY  has  been  looked  upon  as  a  difficult  branch 
of  science,  but  one  finds  it  no  more  difficult  than 
any  of  the  other  branches  of  exact  science.  Any  ex- 
perimental science  requires  a  large  amount  of  study 
and  practice  to  enable  the  worker  to  excel  sufficiently  to 
be  valuable  to  his  fellows.  It  certainly  is  true,  however, 
that,  while  vast  service  has  been  performed  by  chem- 
istry in  adding  to  the  satisfaction  of  civilized  living, 
chemistry  has  not  appealed  to  very  many  people  who 
were  not  themselves  chemists. 

There  seem  now,  however,  to  be  signs  of  an  awaken- 
ing as  to  the  interesting  possibility  of  science  considered 
broadly,  and  there  is  no  doubt  in  the  mind  of  the  writer 
that  chemistry  can  furnish  interesting  subject-matter 
for  general  consideration.  Then,  too,  an  interest  in 
one  subject  will  create  interest  in  another.  Interest 
in  biology  will  easily  and  properly  spread  to  interest 
in  chemistry,  and  vice  versa.  One  cannot  take  up  the 
study  of  agriculture  without  giving  consideration  to 
chemistry. 

How  many  chemical  substances  have  been  elaborated 
by  insects!  We  have  been  calmly  taking  the  results 

1 


2      r ' '-  •          CHLM  iSTK  Y  OF  FAMILIAR  THINGS 

of  their  patient  work  without  much  consideration.  For 
instance,  consider  the  honey-bee.  Any  one  would  be 
interested  in  the  bee  if  he  read  John  Burroughs'  de- 
scription of  the  honey-bee.  One  thing  that  impressed 
the  writer  was  that  we  had  a  wonderful  little  chemist 
in  the  bee.  He  wanted  a  substance  to  make  his  store- 
house and  partition  his  home.  Wasps  use  mud, 
hornets  make  a  crude  paper,  but  the  bee  was  by  far  the 
most  enterprising  and  evolved  a  perfect  plastic  sub- 
stance in  ordinary  beeswax,  one  that  has  never  been 
duplicated  by  man.  We  know,  too,  it  is  always  made 
up  to  standard  in  composition.  Then  we  have  the 
honey,  which  is  made  out  of  all  kinds  of  natural  sugars, 
but  the  bee  converts  them  all  into  honey,  which  is 
practically  laevulose,  a  delicate  and  easily  assimilated 
form  of  sugar.  Commerce  and  industry  have  long  been 
indebted  to  the  lac  insect  for  the  valuable  substance 
shellac,  which  is  the  toughest  resin  we  have.  The 
beautiful  color  cochineal  is  the  specialty  of  another  race 
of  insects  bearing  that  name.  The  bright  red  color 
carmine  is  the  aluminum  compound  of  the  natural 
color.  We  have  also  made  use  of  tannin,  a  variety  of 
which  is  produced  in  plants  by  the  sting  of  insects. 

We  have  the  vast  and  innumerable  elaboration  of 
chemicals  from  the  fungi  and  bacteria,  such  as  alcohol 
and  carbon  dioxide  from  yeasts ;  acetic  acid,  lactic  acid, 
and  other  substances  from  bacteria;  each  organism 
producing  its  kind  and  quota  of  chemical  substances 


INTRODUCTION  3 

so  long  as  the  organism  is  properly  nourished  and  is 
maintained  at  a  suitable  temperature.  Similarly,  all 
other  chemical  processes  need  the  proper  raw  mate- 
rials and  require  certain  limits  of  temperature  for  the 
best  results. 

In  the  realm  of  fibres,  we  have  the  spiders  and  silk- 
worms who  spin  nothing  but  the  finest  filaments.  These, 
human  ingenuity  can  only  approach  in  perfection.  We 
make  artificial  silk  out  of  cotton,  but  it  is  only  a  poor 
substitute  for  the  real  article,  and  we  have  absolutely 
no  way  of  making  anything  with  the  delicacy  of  the 
natural  fibre  from  the  ordinary  spider,  who  seems  to 
have  first  made  nests  or  cocoons,  and  later  discovered 
the  possibilities,  from  a  practical  and  artistic  stand- 
point, of  making  webs. 

In  the  field  of  inorganic  chemistry  we  have  not 
noticed  so  much  activity,  but  mention  might  be  made  of 
the  wonderful  coral  formations  (composed  of  carbonate 
of  lime)  which  have  caused  land  to  rise  above  the  water 
in  tropical  lands.  Much  of  this  lime,  or  maybe  all  of  it, 
has  been  leached  away  from  exposed  limestone  on  hill- 
sides by  the  atmosphere  and  carried  to  the  ocean, 
whence  it  has  been  returned  to  land  again  by  the  coral 
insect.  The  iron  deposits  known  as  log  iron  ore  are 
the  deposits  of  bacteria  which  are  supposed  to  be  nour- 
ished by  iron  which  on  oxidation  supplies  these  queer 
forms  of  life  with  the  necessary  energy,  and  collects 
the  iron  in  masses  for  possible  future  use  by  man. 


4  CHEMISTRY  OF  FAMILIAR  THINGS 

In  the  plant  world  we  find  the  production  of  sub- 
stances of  definite  chemical  composition  so  widespread 
that  they  become  matters  of  the  greatest  economic  im- 
portance. This  refers  to  the  essential  development 
common  to  all  plants,  such  as  the  production  of  car- 
bohydrates, protein,  and  oils  in  the  seeds,  which  are 
designed  to  nourish  the  young  plant  just  as  these  same 
classes  of  substances  do  animals,  and  also  to  the  special 
and  apparently  superabundant  store  of  substances  that 
seem  to  exceed  the  requirements  of  the  plant  for  ordi- 
nary growth. 

"We  have  the  characteristic  vegetable  oils,  such  as 
olive  oil,  linseed  oil,  cottonseed  oil,  cacao  butter,  and 
peanut  oil,  which  undoubtedly  have  a  service  to  per- 
form by  supplying  energy  and  tissue  to  the  young 
plants,  but  are  in  such  great  supply  that  they  are  of  the 
greatest  value  to  man  for  food  and  technical  use.  The 
essential  oils  and  resws  have  some  natural  function, 
such  as  rushing  to  wounded  places  in  the  plant  and 
forming  a  gummy  mass  that  acts  as  a  plaster  to  restrain 
the  wasteful  flow  of  aqueous  sap  or  plant  blood,  which 
comes  when  the  bark  is  cut.  These  essential  oils  or 
oleoresins  (oil  and  resin)  supply  us  with  turpentine 
and  rosin,  camphor  oil  and  camphor. 

Rubber  is  closely  related  to  the  essential  oils,  and 
the  rubber  latex  serves  as  a  healing  salve  as  do  the 
oleoresins.  We  are  also  supplied  with  alkaloids,  such 
as  morphine,  strychnine,  and  quinine,  by  plants.  We 


INTRODUCTION  6 

are  not  sure  just  what  they  do  for  the  plants,  but  they 
seem  potent  enough,  many  of  them,  to  be  effective  for 
some  purpose.  They  may  be  catalytic  substances  that 
induce  the  formation  of  the  plant  proteins  from  nitrates, 
etc.  They  can  hardly  be  the  decomposition  products  of 
the  proteins,  as  the  characters  of  these  substances  are 
known  to  us.  These  manifestations  of  chemistry  in 
nature  are  given  to  show  how  real  and  concrete  is  the 
science  of  chemistry. 

It  might  be  thought  that  enough  chemical  sub- 
stances were  produced  in  nature  so  that  men  did  not 
have  to  make  any.  Even  when  primitive  man  was 
satisfied  with  natural  foods;  and  uncolored  fabrics  made 
of  skin,  etc.,  he  felt  the  need  of  tools  stronger  than  wood 
and  more  readily  shaped  than  stone,  so  the  manufacture 
of  metals  from  the  ores  was  begun.  This  was  a  crude 
smelting  operation,  and  was  probably  carried  out  by 
heating  the  ores  with  some  form  of  carbon  like  charcoal 
and  with  limestone,  with  an  air-blast  to  intensify  the 
heat.  Dye  colors  were  made  from  plants,  such  as 
alizarin  from  madder  root,  indigo  from  the  Indigofera 
tinctoria,  and  many  other  colors  from  roots  and  berries. 
Natural  earths,  such  as  whiting,  clay,  gypsum,  ochres, 
powdered  barks,  roots  and  leaves  were  also  used  before 
chemicals  were  made. 

Little  do  people  see  in  the  changes  occurring  about 
them  anything  that  suggests  the  name  of  Chemistry. 
The  average  person  is  almost  unaware  of  this  im- 


6  CHEMISTRY  OP  FAMILIAR  THINGS 

portant  line  of  thought  and  investigation.  The  signs 
of  the  times  now  seem  to  point,  however,  to  the  popular 
possession  of  a  desire  for  fundamental  and  accurate 
information. 

Exact  knowledge  is  becoming  the  only  kind  that  will 
count  with  both  men  and  women  in  the  near  future. 
The  foregoing  does  not  seem  like  a  dubious  prophecy 
when  those  who  are  able  to  do  so  note  the  changes  made 
in  half  a  generation.  Fifteen  or  twenty  years  ago  ex- 
perts were  few;  now  they  are  found  in  all  pursuits. 
I  am,  therefore,  strongly  of  the  belief  that  it  will  profit 
men  and  women  generally  to  know  accurately  at  least 
a  little  chemistry, — at  least  the  little  that  this  book 
will  afford.  The  day  is  not  far  distant  when  the  average 
business;  man  will  know  that  pure  sand,  silex,  and  quartz 
are  all  silica;  that  soda,  soda  crystals,  soda  ash,  etc., 
are  all  forms  of  sodium  carbonate ;  that  Venetian  red, 
rouge,  and  Indian  red  are  essentially  iron  oxides ;  that 
Glauber's  salt  is  sodium  sulphate;  that  Epsom  salt  is 
magnesium  sulphate;  that  cream  of  tartar  is  acid 
potassium  tartrate  and  tartar  emetic  is  potassium 
antimony  tartrate ;  and  so  on  down  the  list.  It  will  like- 
wise be  found  that  it  will  be  easier  and  better  to  call 
chemical  substances  by  their  scientific  names. 

After  we  grapple  with  a  definition  of  chemistry  and 
find  its  true  place,  we  will  see  if  there  is  not  much  of 
interest  in  a  subject  which  treats  of  the  composition  of 
the  things  about  us. 


CHAPTEE  I 

BEIEF    CHEMICAL   OUTLINE 

EXACT  science  may  be  considered  as  being  composed 
of  four  great  divisions : 

1.  Astronomy  and  mathematics. 

2.  The  natural   or  descriptive  sciences,   such  as 
geology,  botany  and  zoology. 

3.  That  branch  which  studies  matter  in  motion, — 
physics. 

4.  That  branch  which  studies  the  composition  of 
matter, — chemistry. 

Physics  and  chemistry  may  be  briefly  contrasted. 
Some  changes  to  which  matter  is  subjected  are  physical 
and  others  chemical.  In  the  case  of  physical  changes 
the  composition  of  matter  is  not  altered ;  for  instance, 
when  water  is  heated  until  steam  is  evolved.  Steam 
looks  very  different  from  water,  but  there  is  no  altera- 
tion in  composition  in  effecting  this  change.  The  action 
of  heat  merely  lessens  the  mutual  attraction  of  the 
particles  until  finally,  at  the  point  at  which  steam  is 
evolved,  they  repel  each  other  rather  than  attract, 
as  they  did  while  in  the  state  of  water.  An  example  of 

a  chemical  change  is  the  burning  of  gas  or  coal  to  car- 

7 


8  CHEMISTRY  OF  FAMILIAR  THINGS 

bon  dioxide  and  water,  or  burning  hydrogen  in  oxygen 
with  formation  of  water. 

If  substances  in  nature  are  analyzed  or  subjected  to 
processes  of  decomposition,  they  can  often  be  simpli- 
fied, and  the  substances  that  cannot  be  chemically 
simplified  are  known  as  elements;  for  instance,  sodium 
chloride  can  be  split  up  into  sodium  and  chlorine,  but 
we  are  absolutely  unable  to  make  simpler  substances 
out  of  sodium  or  chlorine.  Elements  in  a  chemical 
sense  are  considered  as  ultimate  forms  of  matter. 
Their  identity  is  clearly  established  and  they  enter 
into  combination  with  each  other,  but  are  obtainable 
again  with  their  original  appearances  and  character- 
istics. 

The  simplest  forms  of  matter  are  therefore  known 
as  elements.  There  are  really  only  a  few  of  these 
elements  that  compose  the  earth's  mass  that  are  in 
abundance.  Oxygen  and  silica  comprise  about  three- 
fourths  of  the  entire  solid  crust  of  the  globe.  Seven 
other  elements — aluminum,  iron,  calcium,  magnesium, 
sodium,  potassium,  and  hydrogen — with  the  two  first 
mentioned,  constitute  ninety-nine  per  cent,  of  the  entire 
quantity,  leaving  only  one  per  cent,  for  about  sixty- 
six  of  the  remaining  elements.  Dr.  F.  W.  Clarke  gives 
the  following  estimated  composition  of  the  earth's 
crust,  including  sea  and  atmosphere : 


BRIEF  CHEMICAL  OUTLINE  9 

Oxygen  (O) 49.98  per  cent.      Titanium  (Ti) 0.30  per  cent. 

Silicon  (Si) 25.30  per  cent.      Carbon  (C) 0.21  per  cent. 

Aluminum  (Al) 7.26  per  cent.      Chlorine  (Cl) 0.15  per  cent. 

Iron  (Fe) 5.08  per  cent.      Phosphorus  (P) 0.09  per  cent. 

Calcium  (Ca) 3.51  per  cent.  Manganese  (Mn)  . . .  0.07  per  cent. 

Magnesium  (Mg) ...  2  50  per  cent.      Sulphur  (S) 0.04  per  cent. 

Sodium  (Na) 2.28  per  cent.      Barium  (Ba) 0.03  per  cent. 

Potassium  (K) 2.22  per  cent.      Nitrogen  (N) 0.02  per  cent. 

Hydrogen  (H) 0.94  per  cent.      Chromium  (Cr) 0.01  per  cent. 

Total 99.99  per  cent. 

No  matter  what  forces  are  brought  to  bear  upon 
these  substances,  they  are  not  further  simplified  chem- 
ically. Physically  (mechanically)  pieces  of  any  one 
element,  such  as  iron,  may  be  comminuted  until  the 
particles  are  impalpably  fine,  and  at  the  limit  of  sub- 
division of  which  we  can  conceive  we  would  have  the 
molecules.  However,  every  molecule  is  theoretically 
capable  of  chemical  separation  into  parts,  called  atoms, 
of  which  there  are  generally  two. 

Chemical  affinity  is  the  attraction  or  force  which 
binds  atoms  together  to  form  molecules  and  causes 
interchanges  among  them  when  dissimilar  molecules 
are  brought  in  contact.  Two  atoms  of  the  same  kind 
unite,  or  are  found  in  nature  united,  to  form  simple 
molecules.  Atoms  of  dissimilar  character  also  unite 
to  form  compound  molecules,1  which,  of  course,  are  no 
longer  elements.  If  for  any  reason  an  atom  is  un- 
combined,  due  to  electric  action,  the  influence  of 

1  Simple  atoms  uniting  to  form  molecules  H  +  H  =  H2  (hydrogen 
gas).  Dissimilar  atoms  uniting  to  form  molecules  H -{- H  +  O  =  HgO 
(water).  As  atoms  do  not  ordinarily  exist  alone,  they  are  not  usually 
treated  in  carefully  written  chemical  formulas. 


10  CHEMISTRY  OF  FAMILIAR  THINGS 

radium,  etc.,  it  is  much  more  active  chemically  than 
when  in  the  molecular  condition.  At  the  instant  that 
chlorine,  hydrogen,  or  oxygen,  for  example,  are  liber- 
ated by  electrolysis,  they  are  said  to  be  in  the  nascent 
state  and  will  form  new  combinations  that  they  would 
not  form  in  the  molecular  state. 

All  the  elements  have  abbreviations  used  in  writing 
equations.  They  are  not  always  the  first  letters  or 
abbreviations  of  the  English  words;  some  are  taken 
from  the  Latin,  as  many  of  the  early  chemical  or 
alchemical  works  were  written  in  Latin;  thus,  the 
symbol  for  sodium  is  Na,  a  contraction  of  Natrium,  the 
Latin  name  for  the  metal. 

Equations  are  more  or  less  graphic  ways  of  indi- 
cating that  substances  interacting  produce  one  or  more 
other  substances.  Thus,  hydrochloric  acid  and  sodium 
hydroxide  interacting  produce  sodium  chloride  plus 
water  (HC1  +NaOH  =  NaCl  +  H20).  Subscript  and 
prefixed  numerals  in  formulas  are,  of  course,  simple 
multipliers. 

The  atom  may  be,  and  probably  is,  complex,  but  the 
old  hypothesis  works  admirably  as  yet,  for  we  do  not 
know  how  the  atom  is  constituted,  although  it  is  thought 
by  some  to  be  made  up  of  electrical  vibrations,  and,  if 
so,  matter  is  nothing  but  force  or  energy. 

Hydrogen  (a  colorless  gas)  unites  with  chlorine 
(a  greenish-yellow  gas)  to  form  a  colorless  gas,  which 


BRIEF  CHEMICAL  OUTLINE  11 

is  called  hydrogen  chloride  or  hydrochloric  add  gas 
(H2  +  C12  =  2HC1). 

Sulphur  (a  yellow  solid)  unites  with  (or  burns  with) 
oxygen   to    form   sulphur   dioxide,    a   colorless    gas 


These  last  two  products,  when  in  contact  with  water, 
are  sour  to  the  taste  and  are  called  acids. 

If  the  metal  sodium  be  put  into  water,  there  is  quite 
a  disturbance,  even  with  a  very  small  piece.  A  reaction 
ensues  which  develops  heat.  Hydrogen  gas  is  given  off 
and  the  water  becomes  alkaline  from  the  formation  of 
sodium  hydroxide,  which  is  a  base.  (Na2  +  2H20  = 
2NaOH  +  H2.) 

A  base  is  the  opposite  of  an  acid.  Bases  and  acids 
neutralize  each  other,  with  evolution  of  heat,  to  form 
salts.  It  is  not  very  safe  or  pleasant  to  have  to  taste  a 
mixture  to  find  out  whether  an  acid  is  present.  It  has 
been  known  for  some  time,  however,  that  certain  organic 
substances  have  one  color  with  acids  and  another  with 
bases  or  alkalies.  For  instance,  most  red  vegetable 
colors  turn  blue  or  green  with  alkalies.  Cranberry  juice 
is  naturally  red,  but  if  an  alkali  be  added  it  becomes 
green  ;  so  do  beets,  and  a  red  vegetable  substance  known 
as  litmus,  when  purified,  is  colored  red  with  acids  and 
blue  with  alkalies.  It  is  generally  sold  in  drug  stores  as 
litmus  test  paper,  and  serves  as  an  indicator  for  acids 
and  alkalies. 


12  CHEMISTRY  OF  FAMILIAR  THINGS 

In  the  footnote 2  are  some  examples  of  the  action  of 
acids  and  bases  or  alkalies.  Bases  will  generally  be 
called  alkalies  hereafter,  as  they  are  better  known  by 
that  name.  The  class  of  substances  known  as  salts 
must  not  be  confused  with  common  salt  or  table  salt. 
This  substance  is  only  a  typical  salt,  but  was  the  first 
known,  so  it  gave  the  name  to  the  class  of  similar 
substances  known  as  salts. 

The  practical  side  of  this  subject  is  one  of  daily 
importance  in  the  home,  the  factory,  and  on  the  farm. 
In  the  home  people  have  not  been  accustomed  to  the  use 
of  indicators,  but  they  could  be  used  to  advantage.  To 
be  sure  that  a  water  is  softened  with  washing  soda  an 
indicator,  such  as  litmus  paper,  can  be  used.  "Washing 
soda  would  be  added  to  the  water  until  red  litmus  was 
just  turned  blue.  The  water  would  then  be  soft  and  very 
slightly  alkaline,  enough  to  almost  neutralize  the  slight 
acidity  due  to  the  perspiration  acids  of  the  clothes.  In 
the  factory  and  works  the  use  of  indicators  is  quite 
prevalent,  especially  in  large  works.  In  many  small 

'Acid  Alkali  Salt 

Hydrochloric  acid         Sodium  hydroxide        Sodium  chloride          Water 

HC1  +  NaOH  =  NaCl  +    HjjO 

Sulphuric  acid        Potassium  hydroxide  Potassium  sulphate      Water 
H2S04          +  2KOH  K2SO4  +     2H2O 

A  slightly  different  example  is  where  instead  of  an  hydroxide  we 
use  a  carbonate.  Instead  of  getting  water  alone  in  the  equation,  carbon 
dioxide  is  also  obtained,  thus: 

2HC1  +  Na^OOa  =  2NaCl  +  H20  +  CO2. 


BRIEF  CHEMICAL  OUTLINE  13 

works  they  could  be  used  to  advantage  where  they  are 
not  used  now.  A  leather  manufacturer  could  tell 
whether  his  skins  and  leather  at  various  stages  were 
acid  or  alkaline.  A  dyer  could  judge  of  the  condition 
of  his  dye  vats.  The  soap  maker  could  tell  when  his 
soap  was  neutral.  On  the  farm  or  in  the  vegetable 
garden,  litmus  paper  can  be  used  to  determine  whether 
or  not  the  soil  is  acid.  If  the  soil  turns  moistened  blue 
litmus  red,  it  is  acid,  and  air-slaked  lime  must  be  used 
to  neutralize  it.  Most  grains  and  vegetables  grow  best 
in  neutral  or  slightly  alkaline  soil,  while  weeds  thrive 
in  an  acid  soil. 

Inorganic  acids  and  alkalies  unite  to  form  salts. 
Organic  acids  unite  with  alkalies  to  form  soaps.3 

These  soaps  when  pure  are  neutral  to  suitable  indi- 
cators, and  phenolphthalein  in  alcohol  solution  is  used 
in  this  case  rather  than  litmus.  They  respond  to  the 
test  for  organic  material,  as  the  organic  matter  burns 
off  when  sufficiently  heated  and  leaves  an  inorganic 
residue  which  is  always  a  carbonate  (a  form  of  alkali, 
as  we  have  seen).  It  is  called  a  mild  alkali  or  a  car- 
bonated alkali  and  it  turns  red  litmus  blue.  Soaps  will 
be  treated  later  in  detail  (p.  262). 

As  this  earth  was  formed  by  a  process  that  brought 

3  Oleic  acid  +  sodium  hydroxide  ( NaOH )  =  sodium  oleate  ( a  soap ) 
.+  water.  Stearic  acid  +  potassium  hydroxide  =  potassium  stearate 
+  water. 


14  CHEMISTRY  OF  FAMILIAR  THINGS 

it  through  a  state  of  being  a  molten  mass  at  a  white 
heat,  there  could  not  have  existed  plant  or  animal  life 
until  relatively  recently,  when  it  had  cooled  off  at  the 
surface.  Possibly  for  this  reason  and  because  of  its 
greater  simplicity,  inorganic  chemistry  was  studied 
first  and  has  first  place  in  all  discussions  of  chemistry 
that  are  complete  in  their  scope.  Inorganic  chemistry 
is  essentially  mineral  chemistry.  Most  of  the  inorganic 
elements  usually  occur  combined  in  nature.  Oxygen 
occurs  uncombined  in  the  air,  although  mixed  with 
nitrogen.  Sulphur  occurs  free  in  a  few  places  because 
of  volcanic  or  similar  action.  In  the  cases  of  the  metals, 
only  a  few  are  found  in  the  free  state,  such  as  copper 
(in  a  few  localities),  and  the  so-called  noble  metals — 
silver,  gold,  and  platinum — are  quite  apt  to  be  found  in 
the  free  state,  as  they  are  not  very  subject  to  atmos- 
pheric influences. 

Organic  chemistry  is  the  study  of  the  composition, 
properties,  and  changes  undergone  in  substances  of 
animal  or  vegetable  origin.  Organic  chemistry  is  essen- 
tially the  study  of  the  compounds  of  carbon.  They  are 
composed  largely  of  compounds  of  carbon  and  hydro- 
gen, with  or  without  other  non-metallic  substances, 
such  as  oxygen,  nitrogen,  chlorine,  sulphur,  etc.,  and 
only  occasionally  a  metal  may  be  in  combination. 

One  of  the  early  lessons  we  had  at  school  was  that 
there  were  three  great  divisions  of  matter, — animal, 


BRIEF  CHEMICAL  OUTLINE  15 

vegetable,  and  mineral.    We  might  combine  this  classi- 
fication with  a  simple  chemical  one: 

Animal    )  ( Non-metals  ) 

>  Organic  Mineral  •<  >  Inarganic 

Vegetable)  (     Metals      ) 

Organic  substances  can  generally  be  distinguished 
from  inorganic  ones  by  means  of  heat  in  the  presence 
of  air  at  a  burning  temperature.  Organic  substances 
are  consumed,  while  nearly  all  inorganic  ones  are  not. 
Elements  like  mercury,  arsenic,  and  chlorine,  or  com- 
pounds like  carbon  dioxide,  ammonia,  and  sulphur 
dioxide,  are  a  few  of  the  inorganic  substances  that  are 
likely  to  pass  off  when  decomposable  substances  are 
subjected  to  Burning  conditions,  because  of  their  vola- 
tility. Nearly  all  organic  substances  have  some  ash,  or 
mineral  residue,  when  burned.  Plants  and  animals 
cannot  grow  without  mineral  matter,  such  as  potassium 
salts,  phosphates,  and  ammonium  salts  (or  nitrates). 
They  need  all  three,  and  all  complete  fertilizers  have 
all  three  substances  or  what  will  produce  them.  There- 
fore some  mineral  matter  will  remain  on  burning 
vegetables,  meat,  or  other  organic  tissues,  but  they  are 
essentially  consumed. 

There  are  many  chemical  substances  that  cannot 
be  treated  here,  especially  organic  substances,  of  which 
there  are  a  vast  number,  and  they  are  very  complex  in 
their  constitution  in  many  cases.  Examples  of  some 


16  CHEMISTRY  OF  FAMILIAR  THINGS 

simple  organic  substances  where  there  is  no  admixture 
with  one  or  more  other  substances,  are  ethyl  (grain) 
alcohol,  glycerin,  starch,  and  sugar.  Examples  of 
organic  materials  that  are  mixtures  of  several  simple 
organic  substances  are  petroleum  oils,  vegetable  and 
animal  oils,  woody  tissue,  fibres  of  silk  and  wool,  flour, 
meat,  and  other  animal  and  vegetable  food  materials. 
Included  in  organic  substances  are  such  general  classes 
as  hydrocarbons,  as  in  petroleum ;  alcohols,  such  as  ordi- 
nary ethyl  alcohol  and  wood  alcohol ;  phenols,  such  as 
carbolic  acid  and  thymol;  aldehydes,  such  as  formal- 
dehyde; acids,  such  as  oleic  or  benzoic;  ethers,  such  as 
ordinary  ether,  used  for  anaesthesia;  esters,  such  as 
the  delicate  flavoring  in  fruits  and  wines;  carbo- 
hydrates, such  as  glucose  and  sugar;  organic  bases, 
such  as  pyridine,  from  which  many  alkaloids  are  de- 
rived ;  proteins,  such  as  are  found  in  all  flesh  and  vege- 
tables. 

Besides  the  formation  of  salts  and  soaps,  probably 
the  most  important  reactions  of  a  very  general  nature 
are  oxidation  and  the  opposite  operation  of  reduction. 

On  oxidation  a  substance  is  affected  by  the  reaction 
with  oxygen  or  its  equivalent.  In  the  case  of  reduction, 
the  substance  is  affected  by  the  action  of  hydrogen  or  its 
equivalent.  A  substance  becomes  oxidized  when  oxygen 
or  its  equivalent  is  added  on  or  hydrogen  is  removed, 
and  reduction  is  just  the  opposite.  Oxidation  of  in- 


BRIEF  CHEMICAL  OUTLINE  17 

organic  substances  is  not  of  as  great  importance  in 
the  present  consideration  as  in  the  case  of  organic 
substances.  Organic  substances  seem  to  be  more  sub- 
ject to  change  than  inorganic,  and  one  very  frequent 
change  observed  in  nature,  or  carried  out  designedly,  is 
that  of  oxidation.  If  the  oxidation  be  very  rapid  it  is 
frequently  accompanied  by  flame  or  glow.  Substances 
may  oxidize  without  burning,  but  all  burning  substances 
are  being  oxidized.  Slow  oxidization  does  not  generate 
enough  heat  to  render  the  substance  luminous. 

Examples  of  inorganic  oxidation  are  when  metals 
are  heated  in  air.  Copper  when  heated  to  redness  takes 
on  oxygen  and  changes  from  an  orange-colored  metal 
to  a  black,  easily  broken  mass  that  is  called  copper 
oxide.4 

The  metal  sodium  has  such  a  strong  affinity  for 
oxygen  that  it  is  changed  to  oxide  5  quickly,  especially 
on  the  exposed  surfaces,  by  contact  with  the  air  at  ordi- 
nary temperatures.  If  this  sodium  oxide  be  wetted 
or  allowed  to  remain  in  a  damp  atmosphere,  it  takes  on 
water  and  becomes  sodium  hydroxide. 

The  oxidation  of  organic  substances  is  exemplified 
by  countless  instances  in  what  we  see  around  us.  The 
burning  of  coal  or,  better,  of  charcoal  is  one  of  the 

42Cu   +      O2     =        2CuO 
Copper      Oxygen      Copper  oxide 
B2Naa     +    2H20    =        2NaaO          +        2H2 
Sodium         Water         Sodium  oxide         Hydrogen 

2 


18  CHEMISTRY  OF  FAMILIAR  THINGS 

simplest  cases  of  oxidation.6  The  black  solid  substance 
is  consumed  by  oxygen  to  form  the  odorless,  colorless 
gas,  carbon  dioxide.  This  gas  has  weak  acid  properties 
when  mixed  with  water  and  forms  carbonates  with 
alkalies.  (See  page  12.)  If  the  combustion  be  incom- 
plete, being  conducted  with  a  minimum  amount  of  air, 
carbon  monoxide  7  is  formed.  This  gas  is  colorless,  has 
a  faint  odor,  and  is  poisonous  when  inhaled.  It  can 
be  burned  to  carbon  dioxide8  when  sufficient  air  is 
present.  Carbon  monoxide  is  one  of  the  chief  com- 
ponents of  most  city  gas  and  commercial  producer 
gas.  (See  page  40.)  Carbon  can  only  be  burned  when 
the  combustion  is  started  by  applied  heat  except  in  rare 
cases  (spontaneous  combustion,  page  55).  This  is 
very  fortunate,  or  we  would  not  be  able  to  get  coal 
to  the  furnace  before  it  would  be  burned. 

All  organic  matter  will  oxidize  more  or  less  rapidly 
when  conditions  are  favorable.  Matter  that  contains 
carbon  and  hydrogen  when  oxidized  forms  gases  such 
as  carbon  dioxide  and  water  vapor.  Smoke  that  issues 
from  chimneys  contains  chiefly  these  gases  when  white, 
and  when  the  smoke  is  dark  colored  there  are  uncon- 
sumed  carbon  and  fine  dust  of  ashes  present. 

A  chemical  action  (or  reaction,  as  it  is  generally 
called)  is  governed  by  the  affinity  of  elements  for  each 

•  C  +  Oa  =  C0a.      T  20  +  02  =  2CO.        8  2CO  +  Oa  =  2CO2. 


BRIEF  CHEMICAL  OUTLINE  19 

other.    This  may  be  shown  by  the  accompanying  illus- 
trations made  by  the  author. 

In  Plate  I  (left)  there  was  a  one  per  cent,  solution 
of  silver  nitrate  in  water,  a  little  mercury  was  added 
which  went  at  once  to  the  bottom  of  the  beaker.  It  was 
caught  in  a  small  receptacle  which  caused  it  to  remain 
as  a  globule  in  the  centre.  Mercury  has  greater  affinity 
for  the  nitric  radicle  (NO3)  than  silver,  so  mercury 
goes  into  solution  and  silver  comes  out.  Silver  alloys 
with  excess  of  mercury  present  and  forms  needle-like 
crystals  which  grow  to  form  beautiful  shapes  of  plant- 
like  growth.  This  growth  has  been  called  "  arbor 
Dianae."  Diana  was  an  early  name  given  to  silver. 

Mercury      Silver  nitrate      Mercurous  nitrate      Silver 
Hga      +        2AgN03      =  2HgN03         +    Aga 

In  the  other  illustration  (on  right)  a  strip  of  zinc 
was  dipped  into  a  clear  solution  of  lead  acetate.  The 
zinc  has  greater  affinity  for  the  acetate  radicle  than 
lead,  so  they  change  places  and  the  lead  crystallizes 
quite  rapidly  in  loose,  moss-like  forms. 


CHAPTEE  II 

HISTORICAL,  DEVELOPMENT  OF  CHEMISTEY 

QUITE  a  number  of  world-famous  structures  built 
over  a  thousand  years  ago  have  been  the  wonder  of 
succeeding  ages  until  to-day.  Exact  science  is  quite  re- 
cent, however.  Electricity  was  hardly  known  one  hun- 
dred years  ago,  and  modern  chemistry  had  its  begin- 
ning in  the  forepart  of  the  nineteenth  century.  Chem- 
istry is  really  a  recent  science,  but  many  individual 
operations  now  called  chemical  were  practised  by  the 
Chinese,  Egyptians,  Greeks,  and  others,  long  before 
the  Christian  Era.  The  Chinese  had  smelted  ores  and 
obtained  metals  therefrom  as  early  as  1800  B.C. 

Everybody  has  heard  of  the  alchemists.  They  were 
groping  for  two  things.  The  belief  was  prevalent  dur- 
ing this  era  that  a  way  was  to  be  found  to  convert  baser 
metals  into  gold.  They  thought  that  the  coexistence  of 
lead,  tin,  silver,  and  gold,  for  instance,  in  nature  indi- 
cated a  transmutation  of  one  into  the  other,  as  the  prop- 
erties seemed  to  be  graded,  with  gold  as  the  final  stage. 
They  also  sought  a  means  of  greatly  prolonging  life. 
There  were  undoubtedly  honest  workers  who  believed 
that  they  would  find  out  how  to  make  gold,  but  there 
were  also  impostors  who  showed  how  gold  was  made 
20 


HISTORICAL  DEVELOPMENT  OF  CHEMISTRY  21 

by  surreptitiously  throwing  pieces  of  gold  into  their 
crucibles  while  going  through  some  process.  They 
must  have  collected  much  money  from  would-be  part- 
ners, investors,  or  patrons.  During  the  time  to  which 
we  refer  there  were  great  efforts  made  to  find  the  eliocir 
of  life  and  the  Philosopher's  stone.  The  latter  seemed 
to  be  something  that  when  fused  with  a  baser  metal 
would  produce  gold. 

From  works  in  the  author's  possession,  astrology 
seemed  to  play  some  part  in  alchemy,  and  this  is  not 
to  be  wondered  at,  as  this  pseudo-science  was  much 
practised  during  the  middle  ages  and  its  influence  sur- 
vived probably  until  the  beginning  of  the  eighteenth 
century. 

After  alchemy  had  been  well  under  way,  Paracelsus 
(1493-1541),  a  Swiss,  introduced  the  study  of  chem- 
istry for  medical  purposes.  This  line  of  research  was 
called  lot ro chemist r y ,  and  it  did  much  to  extend  the 
science  of  chemistry,  although  it  may  not  have  done 
much  for  suffering  humanity.  The  next  development 
was  based  upon  an  entire  misconception  of  what  hap- 
pens when  substances,  particularly  metals,  are  heated 
strongly  in  the  air.  Hooke  (1635,  the  inventor  of 
watches)  and  later  Stahl  (1660-1734)  were  among  the 
first  to  study  combustion.  Stahl  thought  that  when  a 
metal  was  stongly  heated  in  the  air  it  was  dissociated 
into  two  components, — the  calx  (oxide)  of  the  metal 


22  CHEMISTRY  OF  FAMILIAR  THINGS 

and  phlogiston,  a  gas.  There  was  a  great  contradiction 
in  their  reasoning.  The  metals  increased  in  weight 
after  the  driving  off  of  this  so-called  phlogiston  be- 
cause, as  we  now  know,  oxygen  was  taken  on  from  the 
air,  but  they  explained  the  phenomenon  by  saying  that 
phlogiston  was  driven  off  by  heat  and  as  it  had  minus 
weight  the  calx  could  weigh  more  than  the  metal. 

The  fallacious  theories  of  phlogiston  were  soon 
followed  by  a  series  of  discoveries  of  the  true  elements, 
or  ultimate  components  of  substances.  It  might  be 
interesting  to  note  a  few  of  the  more  important  of 
these.  Black  noticed,  on  heating  magnesium  carbonate 
to  redness,  that  a  gas  was  given  off  which  he  called 
' i fixed  air"  (carbon  dioxide)  because  it  would  not  take 
part  in  combustion.  This  gas,  indeed,  is  not  an  ele- 
ment, as  it  is  divisible  into  its  components,  carbon  and 
oxygen;  but  this  accurate  observation  shows  that  in- 
vestigators were  now  on  the  path  towards  finding  the 
true  components  of  matter.  He  also  recognized  the 
fact  that  the  same  gas  was  obtained  by  adding  acids 
to  magnesium  carbonate,  burning  carbon,  or  in  breath- 
ing. This  was  a  wonderful  contribution  to  chemistry 
for  this  period.  Black  also  discovered  that  solids,  liq- 
uids and  gases  could  absorb  heat  which  might  remain 
latent  (be  stored),  as  when  a  solid  was  liquefied  or  a 
liquid  was  vaporized;  this  was  called  latent  heat;  and 
he  noticed  that  all  substances  possessed  a  certain 


HISTORICAL  DEVELOPMENT  OF  CHEMISTRY  23 

amount  of  heat  at  any  temperature,  called  specific  heat. 
Thus,  water  holds  more  heat  than  copper,  and  copper 
more  than  lead,  at  any  definite  temperature. 

The  most  brilliant  investigator  in  his  day  was 
Priestley  (1735-1804),  who  late  in  life  lived  in  this 
country.  Priestley  discovered  oxygen  (which  he  called 
dephlogisticated  air),  nitrogen,  nitrous  oxide,  nitric 
oxide  and  carbon  monoxide.  Cavendish  (1731-1810) 
was  a  very  brilliant  experimenter,  and,  while  he  did  not 
discover  many  elements,  he  did  some  very  exact  work, 
such  as  finding  that  air  is  a  definite  mixture  of  oxygen 
and  nitrogen.  He  discovered  hydrogen,  and  found 
that  when  hydrogen  was  burned  in  air  water  alone 
was  formed,  thus  establishing  the  composition  of 
water. 

A  great  generalization  was  discovered  or  announced 
by  the  brilliant  French  chemist  Lavoisier.  This  is  so 
important  that  it  should  be  emphasized.  Matter  is 
indestructible.  Nothing  is  lost  in  the  universe.  If  one 
burns  oil  in  a  lamp  the  weight  of  the  products  of  com- 
bustion, water  (H20)  from  the  burning  hydrogen  (H2) 
of  the  oil  and  carbon  dioxide  (C02)  from  the  burning 
carbon  (C2)  of  the  oil  exactly  equals  the  weight  of  the 
oil  plus  the  weight  of  oxygen  uniting  with  the  oil  dur- 
ing combustion.  If  copper  be  heated  to  redness  in  the 
air  it  unites  with  oxygen,1  and  the  gain  in  weight 


24  CHEMISTRY  OF  FAMILIAR  THINGS 

exactly  corresponds  to  the  oxygen  absorbed.  Nowhere 
is  the  indestructibility  of  matter  so  clearly  shown  as  in 
nature.  Not  even  a  leaf  that  falls  from  the  tree  is 
wasted,  for  sooner  or  later  all  its  carbon  returns  to  the 
air  as  carbon  dioxide  and  the  hydrogen  forms  water 
again.  The  mineral  residue  improves  the  fertility  of 
the  soil.  Berthollet  (about  1800)  published  a  work  in 
which  he  claimed  that  elements  united  with  each  other 
because  of  chemical  affinity,  which  he  recognized  as  a 
force  something  like  gravity. 

This  was  a  very  important  period  at  the  beginning 
of  the  nineteenth  century,  for  elements  had  been  dis- 
covered on  and  off  for  a  century;  the  list  of  ele- 
ments now  undoubtedly  is  incomplete,  but  there  were 
generalizations  introduced  at  this  time  which  are  the 
fundamental  laws  of  chemistry  to-day.  Proust  (1801- 
1806)  announced  that  elements  combine  in  definite 
proportions ;  for  instance,  about  23  parts  by  weight  of 
siodium  always  require  about  35.5  parts  of  chlorine  for 
combination  to  make  sodium  chloride  (table  salt). 
Dalton  then  found  that  an  element  could  combine  with 
more  than  one  proportion  of  some  elements,  but  still 
the  quantities  were  fixed  and  simple  multiples  of  the 
least  quantity.  Mercury  combines  with  two  fixed 
quantities  of  oxygen,  nitrogen  with  as  many  as  five 
different  but  fixejl  quantities  of  oxygen.  Proust's  law 
is  the  law  of  definite  proportions  and  Dalton *s  is  the 


HISTORICAL  DEVELOPMENT  OF  CHEMISTRY  25 

law  of  multiple  proportions.  The  first  law  enables  us 
to  calculate  exactly  the  proportions  to  be  used  when  we 
want  to  carry  out  a  chemical  process.  For  instance, 
if  we  want  to  neutralize  the  fatty  acid  in  an  oil,  we 
ascertain  the  amount  required  in  a  small  sample,  say 
a  gramme,  by  cautiously  adding  an  alkaline  solution  of 
known  strength,  and  we  then  add  the  calculated  amount 
of  alkali  to  the  large  batch.  When  the  proportions  of 
two  elements  vary  according  to  the  second  law,  we 
generally  say  they  are  in  different  states  of  oxidation. 
When  mercury  has  one  atom  of  chlorine  (HgCl)  it  is 
called  mercurous  chloride  or  lower  state  of  oxidation 
(chlorine  being  considered  like  oxygen),  and  when  it 
has  two  atoms  of  chlorine  it  is  called  mercuric  chloride 
(HgCl2).  These  affixes,  ous  and  ic,  always  have  the 
same  significance,  and  indicate  whether  a  metal  has  or 
has  not  the  maximum  amount  of  non-metal  in  com- 
bination. 

During  the  eighteenth  century  there  were  some  im- 
portant laws  of  gases  discovered  by  Boyle  and  others. 
Such  important  principles  as  that  a  gas  expands  di- 
rectly as  the  temperature  were  enunciated.  We  see 
exemplifications  of  this  in  the  formation  of  air  cur- 
rents. When  an  area  becomes  heated  the  air  expands 
and  is  made  lighter.  It  then  ascends,  and  air  is  drawn 
from  other  sections  to  fill  the  partial  vacuum.  The 
compression  of  a  gas  creates  heat  and  the  expansion 


26  CHEMISTRY  OF  FAMILIAR  THINGS 

of  a  gas  absorbs  heat  (seems  to  create  cold).  Applica- 
tion of  this  property  of  gases  is  made  in  the  artificial 
creation  of  cold. 

Just  when  modern  chemistry  began  is  hard  to  say. 
A  few  modern  chemical  substances,  by  other  names  in 
most  cases,  were  known  in  early  Eoman  times,  as  shown 
by  the  writings  of  observers  like  Pliny.  There  was, 
however,  little  real  progress  made  until  the  eighteenth 
century,  when  some  of  the  most  important  chemical 
elements  were  discovered,  as  we  have  seen.  About 
the  beginning  of  the  nineteenth  century  chemical  sub- 
stances were  crudely  classified,  although  the  names  of 
most  of  these  substances  did  not  follow  our  present 
nomenclature.  They  spoke  of  1 1  vegetable  alkali ' '  when 
they  meant  potassium  salts,  "mineral  alkali "  for  so- 
dium salts,  "volatile  alkali"  for  ammonium  salts  and 
combinations.  They  had  the  right  idea,  however,  by 
this  time. 

It  was  early  in  the  nineteenth  century  when  sul- 
phuric acid  and  sodium  hydroxide  were  made  on  a 
large  scale,  and  that  might  be  said  to  have  been  the 
beginning  of  the  modern  chemical  epoch.  The  most 
recent  portion  of  this  era  has  been  replete  with  the 
production  of  the  finer  organic  chemicals,  such  as 
artificial  dye  colors,  synthetic  remedial  agents,  and 
electric  furnace  products,  such  as  artificial  graphite 
and  carborundum,  calcium  carbide,  phosphorus,  and 


HISTORICAL  DEVELOPMENT  OF  CHEMISTRY  27 

special  steels  and  alloys.  Electrolytic  sodium  hydrox- 
ide and  sulphuric  acid,  made  by  the  action  of  the  oxygen 
of  the  air  on  sulphur  dioxide  in  the  presence  of  a  cata- 
lytic or  contact  substance,  are  also  great  modern  im- 
provements in  the  chemical  field,  and  "air  saltpeter/' 
or  nitrate,  made  by  the  union  of  the  nitrogen  and 
oxygen  of  the  air  under  the  influence  of  the  spark  dis- 
charge of  the  electric  arc,  is  rising  in  importance. 

Plastic  substances,  such  as  vulcanite,  celluloid  (a 
vulcanized  fibre  made  by  the  action  of  zinc  chloride  on 
paper),  and  a  very  recent  plastic  made  from  carbolic 
acid  by  the  action  of  formaldehyde,  called,  from  the 
inventor,  "Baekelite,"  are  chemical  products  of  the 
last  half  century.  We  will  see,  as  we  go  on,  what 
chemistry  has  done  for  many  of  the  important  indus- 
tries, with  the  exception  of  the  purely  chemical  in- 
dustries, such  as  the  manufacture  of  chemicals  them- 
selves. These  important  lines  of  work  are  not  directly 
of  interest  to  the  average  person,  so  they  will  not  be 
discussed  here,  as  this  book  is  designed  to  be  the 
"  Chemistry;  of  Familiar  Things. " 


CHAPTER  HI 

THE  PEKIODIC  SYSTEM  OF  ELEMENTS 

CHEMISTRY  possesses  a  sort  of  revelation.  It  is 
called  the  periodic  system.  This  system  is  nothing  else 
than  a  list  of  the  elements  in  the  order  of  their  atomic 
weights,  or  weights  of  the  elements  relative  to  the 
weight  of  the  hydrogen  atom,  forming  several  series  in 
horizontal  lines  so  arranged  that  similar  elements 
occur  in  vertical  rows. 

Elements  are  grouped  according  to  relationship,  a 
few  of  which  are  as  follows,  and  these  groups  or 
families  are  found  in  the  same  columns  in  the  periodic 
system. 


GROUPS 

Sodium 

Calcium 

Carbon 

Oxygen 

Chlorine 

Lithium 
Sodium 
Potassium 
Rubidium 
Calcium 

Glucinum 
Magnesium 
Calcium 
Strontium 
Barium 

Carbon 
Silicon 
Germanium 
Tin 

Oxygen 
Sulphur 
Selenium 
Tellurium 

Fluorine 
Chlorine 
Bromine 
Iodine 

This  revelation  of  the  orderly  sequence  of  the 
atomic  weights  going  hand-in-hand  with  a  gradation 
in  properties  of  the  elements  was  discovered  nearly 
simultaneously  by  Lothar  Meyer  in  Germany  and 
Mendeleeff  in  Russia  in  1868.  It  was  found  that  there 
were  some  gaps  in  the  table,  and  Mendeleeff  went  so  far 

28 


THE  PERIODIC  SYSTEM  OF  ELEMENTS  29 

as  to  predict  what  would  be  the  properties  of  elements 
for  these  places,  should  they  ever  be  discovered. 
Vacancies  have  now  been  filled  by  the  discovery  of 
gallium,  scandium,  and  germanium,  besides  a  complete 
series  of  air  gases :  helium,  neon,  argon,  krypton,  and 
xenon. 

When  the  principle  of  the  periodic  system  was 
enunciated,  chemists  began  to  speculate  as  to  the  com- 
position of  matter  afresh,  and  ever  since  this  time 
efforts  have  been  made  to  solve  the  riddle.  It  was  first 
thought  that  all  matter  was  built  up  from  hydrogen, 
as  the  elements  at  first  seemed  to  have  atomic  weights 
of  multiples  of  one  or  integers,  but  now  accurate  work 
has  shown  that  not  many  of  them  are  whole  numbers. 
The  belief  is  still  prevalent  that  all  elements  are  ag- 
gregate^ of  sonne  primordial  substance  other  than 
hydrogen. 

The  analogy  of  the  periodic  system  to  the  har- 
monic series  of  music  is  very  striking.  Elements  of 
like  character  recur  just  the  same  as  musical  notes  of 
like  character.  Sodium,  which  is  much  like  lithium, 
has  an  atomic  weight  that  brings  it  in  the  same  vertical 
row  as  lithium,  and  potassium  comes  under  sodium, 
and  each  is  sixteen  more  in  atomic  weight  than  the 
one  above  it.  Further  down  the  column  the  interval 
between  related  elements  in  the  vertical  row  is  more 
than  sixteen.  <  ~  - 


30  CHEMISTRY  OF  FAMILIAR  THINGS 

Germanium  had  not  been  discovered  when  the 
principle  of  the  periodic  system  was  enunciated.  One 
of  the  elements  which  Mendeleeff  anticipated,  should  it 
be  found,  might  fill  this  void  in  the  table  was  called 
by  him  eka-silicon.  He  described  its  properties  which 
were  to  be  midway  between  those  of  silicon  (Si)  and 
tin  (Sn).  Germanium  (Ge)  when  discovered  was  found 
to  occupy  this  place  in  the  table  both  because  of 
its  atomic  weight  and  the  properties  it  possessed.  Eka- 
silicon  was  then  removed  from  its  place  as  substitute 
and  germanium  has  occupied  it  ever  since.  This  shows 
the  great  importance  of  the  periodic  system.  Some 
scientists  think  some  of  the  still  missing  members  of  a 
completed  table  might  exist  in  other  planets  and  on 
this  earth,  and  that  in  the  original  nebula  from  which 
the  planets  came  all  elements  that  have  places  in- 
dicated in  the  periodic  system  were  to  be  found.  It 
would  be  a  wonderful  demonstration  of  the  complete- 
ness with  which  nature  develops  systematic  relation- 
ships if  this  were  the  case. 


CHAPTER  IV 

THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT 

LIGHT  itself  is,  primarily,  a  mechanical  or  physical 
manifestation.  Chemistry,  however,  plays  a  very  im- 
portant part  in  the  artificial  creation  of  light,  and,  as 
we  have  that  to  deal  with  particularly,  it  does  not  seem 
inappropriate  to  devote  a  chapter  to  illumination. 
Light  is  intangible.  It  cannot  be  weighed  as  air  can, 
but  is  a  manifestation  of  energy  and  is  transmitted 
through  space,  where  there  is  air  or  through  a  vacuum, 
through  glass  or  water,  by  a  wave-like  motion  of  a 
hypothetical,  highly  attenuated  fluid  known  as  ether. 
This  does  not  mean  the  liquid  used  for  anaesthesia, 
but  the  name  in  this  connection  refers  to  the  medium  of 
propagation  of  impulses  such  as  those  of  heat  and 
light. 

Sound  waves  are  different  from  heat  and  light,  as 
they  can  only  travel  in  dense  media,  such  as  air,  water, 
metals,  etc.,  and  they  travel  faster  in  the  latter  than  in 
the  former.  The  subject  of  vibratory  impulses  has 
been  so  thoroughly  studied  that  the  lengths  and  the 
frequency  of  the  various  kinds  of  wave  motions  have 
been  measured  accurately  and  the  knowledge  gained 
has  accounted  for  many  observed  happenings.  When  a 

31 


32  CHEMISTRY  OF  FAMILIAR  THINGS 

piece  of  iron  is  slowly  heated  in  the  flame,  it  at  first 
radiates  heat,  and  as  the  frequency  of  the  wave  motions 
becomes  greater  it  radiates  light, — first,  red  rays,  then 
yellow,  and  finally,  if  the  heat  be  very  intense,  a  white 
light  is  emitted.  The  red  waves  are  longer  and  of  less 
frequency  than  the  blue.  "When  white  light  passes 
through  a  glass  prism,  the  waves  are  differently  acted 
upon  and  are  separated.  The  red  rays  are  diverted 
less  from  their  previous  direction  than  the  violet, 
which  accounts  for  the  separation  of  the  colors  in  a 
prism  projection.  This  is  exemplified  in  light  from  a 
clear  sky.  Eef racted  by  suspended  particles,  the  blue 
rays  are  diverted  more  than  the  others  and  give  the 
blue  appearance  to  the  otherwise  colorless  clear  sky. 
The  color  of  water  when  relatively  clear  and  of  moder- 
ate depth  is  due  to  very  finely  suspended  matter  which 
deflects  some  rays  of  light  more  than  others.  It  may 
thus  look  green  or  blue,  due  to  the  amount  of  deflection. 
Besides  the  wave  lengths  producing  the  ordinary  colors 
of  the  spectrum  which  affect  the  retina  of  the  eye,  there 
are  those  of  less  frequency  than  red  and  others  of 
greater  frequency  than  violet.  They  are  known  as 
infra-red  and  ultra-violet  rays.  These  ultra-violet  rays 
affect  the  photographic  plate  and  have  a  good  deal  of 
interest  in  other  ways.  Ultra-violet  light,  for  instance, 
is  sterilizing  in  its  effect  and  induces  chemical  changes. 


THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT          33 

The  colors  at  the  red  end  of  the  spectrum  give  the 
most  heat,  in  the  middle  the  most  light,  and  the  ultra- 
violet is  the  most  active  in  producing  chemical  change 
but  gives  very  little  heat. 

Light  travels  through  space  in  straight  lines  with  a 
velocity  of  about  186,000  miles  (equal  to  over  seven 


Fio.  1. — Solar  spectrum. 

times  around  the  world)  in  a  second.  The  intensity  of 
light  on  a  given  surface  is  inversely  as  the  square  of  the 
distance  from  its  source.  At  twice  the  distance  a  given 
unit  of  surface  receives  one-fourth  the  light.  It  would 
seem  that  a  given  amount  of  light  placed  in  different 
parts  of  a  room  would  give  better  results  than  if  placed 
as  one  source  of  light.  Light  diffused  by  ground  glass 
is  easier  on  the  eyes,  because  of  its  lessened  intensity. 


34  CHEMISTRY  OF  FAMILIAR  THINGS 

Light  is  reflected,  absorbed,  or  transmitted  by 
bodies  upon  which  it  impinges.  A  transparent  object 
is  one  that  transmits  most  of  the  light  and  reflects  or 
absorbs  very  little.  A  colored  transparent  substance 
is  one  that  transmits  part  of  the  spectrum  and  absorbs 
the  rest.  Bodies  that  are  colored  when  seen  by  re- 
flected light  likewise  absorb  all  but  the  rays  of  the 
color  that  is  reflected  to  the  eyes. 

If  red  is  removed  from  the  spectrum  the  other 
colors  combine  to  form  bluish-green,  or  the  comple- 
mentary color  to  red.  Purple  is  the  complementary 
color  to  green,  ultramarine  blue  to  yellow.  When  re- 
fined sugar  is  slightly  yellowish,  the  color  known  as 
ultramarine  is  added  to  neutralize  the  yellow  and  it 
appears  white.  When  manufacturers  want  to  make  a 
slightly  yellowish  product  look  pure  white,  they  pack 
it  in  bluish  paper,  which  throws  a  blue  light  through  it 
and  neutralizes  the  yellow. 

The  writer  always  had  the  feeling  that  daylight 
was  of  rather  fixed  quality,  but  when  these  proofs 
were  submitted  to  a  friend,  who  was  president  of  the 
National  Illuminating  Engineering  Society,  among 
other  points  he  queried  the  word  normal  as  an  adjective 
used  with  daylight,  for  the  reason  that  daylight  was 
variable  from  an  analytical  point  of  view.  Northern 
light  on  a  clear  day  contains  more  blue  rays  due  to  the 
light  coming  from  the  blue  sky.  Of  course  if  north 


THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT         35 

light  is  reflected  from  a  building  nearby,  it  is  not  true 
north  light  but  a  reflected  south  light,  etc.  The  colors 
of  objects  are  greatly  modified  by  the  incident  light,  as 
all  know  and  have  seen  exemplified  in  theatres  where 
different  colored  lights  are  thrown  upon  the  stage  and 
give  colored  effects  to  objects  upon  which  they  strike. 
Artificial  lights  are  all  different  from  any  variety  of 
daylight  or  even  white  light  (most  daylight  is  a  bluish 
shade  of  white  light) .  A  lantern  *  may  be  used  with  gas 
that  gives  daylight  of  the  northern  sky  variety.  This 
has  been  accomplished  by  the  interposition  of  a  screen 
of  the  right  shade  of  blue.  This  glass  was  not  on  the 
market  and  had  to  be  made  specially  for  the  purpose. 
This  device  is  used  for  matching  colors  in  dyed  or 
printed  goods,  etc.  Daylight  glasses  have  also  been 
made  to  neutralize  yellow  light,  so  that  with  these  spec- 
tacles one  can  see  colors  indoors  as  he  should.  Artificial 
daylight  has  been  made  from  electrical  sources  in  two 
ways:  First,  two  lamps  are  used,  such  as  the  Moore 
lamp,  which  gives  a  yellow  light,  and  a  Cooper-Hewitt 
lamp,  which  gives  a  greenish-blue  light;  the  combina- 
tion of  these  two  is  said  to  be  nearly  the  same  as  day- 
light: second,  a  screen  can  be  used  with  electric  lights 
about  the  same  as  with  gas  mantles. 

Light  is  essentially  reflected  when  it  is  returned 
from  a  surface,  as  from  a  mirror ;  transmitted  when  it 

1  The  invention  of  Dr.  H.  E.  Ives. 


36  CHEMISTRY  OF  FAMILIAR  THINGS 

goes  through  in  a  straight  line,  as  through  a  window- 
pane;  and  refracted  when  it  goes  through  media,  such  as 
glass  or  water,  with  a  difference  in  direction,  taken  at 
the  surfaces  of  the  substance.  Thus,  an  oar  in  the  water 
seems  bent  to  the  eye,  as  the  light  reflected  by  the  oar 
does  not  travel  a  straight  course  to  the  eye.  Interest- 
ing phenomena  connected  with  light  are  those  included 
under  phosphorescence.  Some  mineral  substances  show 
a  luminosity  called  phosphorescence  after  exposure  to 
visible  light  rays  or  invisible  ultra-violet  rays.  This  is 
true  of  barium  platino-cyanate,  calcium  tungstate, 
calcium  sulphide,  etc.  Some  substances,  such  as  wil- 
lemite  (anhydrous  zinc  silicate),  quinine  sulphate,  and 
dyes  such  as  fluorescein,  glow  only  when  excited  by  rays 
such  as  ultra-violet  or  those  evolved  from  radium.  It 
is  supposed  that  the  violet  and  ultra-violet  rays  cause 
a  condition  of  stress  in  the  substance  which  causes  it 
to  give  off  light  for  a  while  in  the  dark.  Fireflies  and 
minute  organisms  in  decaying  wood  seem  to  generate 
light  in  much  the  same  way  that  food  energy  is  con- 
verted into  heat  energy  in  higher  animal  life.  Some 
bacteria  or  protozoa  in  the  water  have  this  effect,  espe- 
cially when  the  water  is  agitated,  as  when  a  person 
swims  in  the  water  and  air  is  introduced.  This  effect 
is  noticeable  to  best  advantage  in  September,  and  if  any 
one  swims  or  the  water  is  splashed  at  night  the  effect 
is  quite  beautiful. 


THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT         37 

Light  has  a  marked  chemical  influence  upon  a  great 
many  substances.  The  bleaching  action  upon  many 
dye  colors  is  well  known  and  is  due  to  the  influence  of 
the  ultra-violet  rays,  chiefly  in  inducing  oxidation  or 
other  chemical  change.  In  the  dark,  linseed  oil  becomes 
deep  in  color,  due  to  a  reducing  action  upon  the  pig- 
ments of  the  oil.  The  direct  sunlight  causes  a  reverse 
action  and  oxidizes  the  pigment  so  that  it  becomes 
colorless. 

White-lead  paint  is  easily  darkened  by  hydrogen 
sulphide  gas,  due  to  the  formation  of  lead  sulphide 
(PbS).  In  the  presence  of  the  ultra-violet  rays  of  the 
sun  the  lead  is  oxidized  in  the  presence  of  the  hydrogen 
sulphide  to  lead  sulphate  (PbS04),  which  is  white,  so 
that  the  white  paint  does  not  seem  to  have  been 
altered,  and  it  is  only  where  hydrogen  sulphide  gas  acts 
on  white  lead  in  the  dark  or  absence  of  strong  light  that 
the  paint  is  discolored. 

According  to  Freer  and  Gibbs,2  the  ultra-violet  rays 
of  direct  sunlight  are  the  cause  of  sunburn,  and  nature 
(with  most  people)  protects  herself  against  their  con- 
tinued influence  by  a  process  of  pigmentation.  This 
pigmentation  became  a  racial  characteristic  with  the  in- 
habitants of  the  tropics,  especially  in  Africa.  These 
same  writers  state  as  a  fact,  what  has  long  been  be- 
lieved, that  the  color  of  the  clothing  has  a  direct  in- 

2  VIII  International  Congress  of  Applied  Chemistry. 


38  CHEMISTRY  OF  FAMILIAR  THINGS 

fluence  on  the  comfort  of  the  individual,  irrespective  of 
the  weight  of  the  goods,  red  clothing  being  more  heat- 
ing than  white.  White  clothing  is  the  coolest,  and,  if 
it  is  loose  and  more  or  less  pervious  to  air,  it  enables 
the  perspiration  to  be  evaporated,  which  is  nature's 
chief  process  for  its  self-cooling. 

The  theoretically  perfect  light  is  one  that  radiates 
no  heat,  such  as  the  light  from  fireflies.  But  while  no 
perfect  light  has  been  made  commercially  as  yet,  there 
have  been  great  strides  in  the  matter  in  recent  years. 
The  Welsbach  gas  mantle  was  the  first  great  step  in 
this  direction,  and  the  last  improvement  in  getting  light 
rather  than  heat  by  the  expenditure  of  energy  was  in 
the  introduction  of  the  tungsten  incandescent  electric 
filament. 

TABLE  OF  LIGHT  EFFICIENCIES.' 

Fireflies     about  100  per  cent. 

Acetylene  flame    4  to  5  per  cent. 

Welsbach  burner    4  to  5  per  cent. 

Carbon  filament,  electric   (4  watts  per  candle)  ....  2  to  3  per  cent. 

Tungsten  filament,  electric  (1.25  watts  per  candle)  8  to  10  per  cent. 

Electric    arcs    8  to  17  per  cent. 

Mercury- vapor  electric  lamps   (glass)    5  to  6  per  cent. 

Nernst  glower 5  per  cent. 

These  are  efficiencies  with  regard  to  the  propor- 
tion of  light  to  total  radiation,  and  do  not  refer  to 
cost  to  the  consumer.  'Ultra-violet  light  not  covered 

'Mostly  from  E.  P.  Hyde:  A  paper  entitled  "  Physical  Characteristics 
of  Luminous  Sources,"  Lectures  on  "  Illuminating,"  Engineering,  vol.  i, 
p.  25. 


THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT          39 

with  glass  is  dangerous  to  the  eye,  for  physiological 
reasons.  Glass  almost  completely  absorbs  ultra-violet 
light,  whilst  quartz  does  not.  The  latter  is  therefore 
used  where  chemical  effect  is  desired,  and  a  glass  cover 
protects  the  eyes  when  used  as  an  illuminant.  Of  the 
present  artificial  light  sources  the  mercury-vapor  lamp 
with  silica  tubes  is  productive  of  the  largest  amount 
of  ultra-violet  light  except  arcs  from  iron  or  silicon. 

A  very  interesting  experiment  that  can  be  per- 
formed in  the  home  is  to  collect  in  a  quart  jar  as  many 
fireflies  as  it  will  hold  to  advantage  (so  that  the  sides 
are  filled  with  them)  and  to  put  it  on  the  centre-table  at 
night  in  a  room  not  otherwise  illuminated.  It  will  be 
found  that  they  create  a  very  mellow  light  that  one  can 
read  by,  and  if  a  long  exposure  is  given  a  photograph 
can  be  taken  by  its  aid.  The  writer  expected  to  collect 
enough  members  of  the  Society  of  Illumination  Flies 
this  summer  to  take  such  a  picture  for  the  purpose  of 
illustration  here, but  neglected,  for  some  reason,  to  do  so. 

The  sources  of  light  most  used  are  gas,  oil,  elec- 
tricity, acetylene,  candles  and  denatured  alcohol. 

Gas  is  obtained  naturally  in  some  localities,  such  as 
Western  Pennsylvania,  West  Virginia,  Ohio,  and 
Kansas,  by  drilling  into  the  deeper  rock  strata,  and 
when  so  obtained  is  a  cheap  source  of  light.  It  is  largely 
composed  of  methane  (CH4),  the  member  of  lowest 
molecular  weight  of  the  series  which  includes  petro- 


40  CHEMISTRY  OF  FAMILIAR  THINGS 

leum  products,  such  as  gasolene,  kerosene,  and  par- 
affin. Gas  may  be  made  artificially,  however,  in  retorts 
by  heating  bituminous  coal.  Besides  gas,  tar  and 
ammonia  are  evolved  and  coke  is  left,  which  is  used  for 
making  iron  in  blast  furnaces  and  for  domestic  use. 

Coal  +  heat  =  coke  +  gas  +  tar  +  ammonia. 

The  composition  of  illuminating  gas  ought  to  be  well 
known  to  everybody.  Most  city  gas  is  a  combination 
product  made  by  driving  steam  through  glowing  coke 
or  hard  coal,  which  is  called  "water  gas."  It  is  essen- 
tially a  mixture  of  hydrogen  and  carbon  monoxide. 
This  gas,  however,  would  not  burn  with  a  yellow  flame, 
so  a  semi-refined  petroleum  product  called  gas  oil  is 
injected  into  the  carburetter  of  the  apparatus  in  which 
the  water  gas  is  made.  This  gives  to  the  gas  the  con- 
stitutents  called  illuminants.  Sometimes  this  carbur- 
etted  water  gas,  as  it  is  called,  is  mixed  with  retort 
gas,  which  comes  from  the  heating  of  bituminous  coal  in 
retorts  or  muffles.  These  additions  to  water  gas  give 
it  odor,  so  that  its  escape  is  easily  detected,  which  is  a 
safeguard. 


Hydrogen    (H)       

52.0 

Water  gas, 
Philadelphia 
1911 

36.05 

Retort 
490 

Carbon  monoxide    (  CO  )    .  .  . 

.  .  .   38.0 

26.30 

7.2 

Methane     (CH4) 

1.0 

21.45 

345 

Illuminants    

11.56 

5.0 

Nitrogen    (N)     

...     3.0 

1.20 

3.2 

Carbon  dioxide    (COg) 

.     6  0 

2.60 

1.1 

Oxygen    . 

0.84 

THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT          41 

Most  city  gas  is  a  highly  refined  product,  as  the  tar 
that  forms  in  the  manufacture  is  very  carefully  re- 
moved and  is  utilized  to  make  many  things  of  value, 
such  as  benzol,  toluol,  and  coal-tar  naphtha  (all  solvents 
for  many  useful  purposes) ;  naphthalene,  a  white,  flaky, 
crystalline  substance,  sometimes  called  coal-tar  cam- 
phor; anthracene,  used  for  making  coal-tar  colors; 
carbolic  acid  and  various  forms  of  disinfecting  creo- 
sotes ;  roofing  pitch,  and  road  oils.  Ammonia  is  washed 
out  with  water  and  is  refined  for  refrigerating  and 
household  use.  Sulphur  compounds  are  absorbed  by 
means  of  specially  prepared  iron  oxide.  These  im- 
purities are  valuable  by-products  that  cheapen  the  cost 
of  making  gas  and  render  it  a  satisfactory  article  for 
use. 

There  is  a  great  deal  seen  in  the  newspapers  about 
coal-tar  colors.  Their  relation  to  coal-tar  is  a  true  one, 
but  they  are  several  generations  removed.  Pure  benzol 
or  pure  toluol  (volatile  liquids  distilled  from  coal-tar) 
are  generally  the  starting-points,  although  naphthalene 
and  anthracene  are  much  used  for  the  colors  fast  to 
light.  If  benzol  is  the  starting-point,  it  is  generally 
treated  with  nitric  acid,  which  makes  nitrobenzene 
(C6H5N02).  This  is  then  by  treatment  with  iron  and 
sulphuric  acid  converted  into  aniline  (C6H5NH2),  from 
which  the  colors  are  made  by  special  reactions.  The 


42  CHEMISTRY  OF  FAMILIAR  THINGS 

color  known  as  "butter  yellow "  is  made  from  aniline 
by  treatment  with  nitrous  acid.  In  country  houses  gas 
made  by  passing  air  over  gasolene  is  often  used.  This 
kind  of  gas  is  practically  non-poisonous. 

Oil  is  obtained  by  the  distillation  of  crude  petroleum 
in  large,  horizontal,  cylindrical  vessels  holding  one 
thousand  barrels  each.  Gases  come  over  first,  which 
a  passage  through  a  condenser  fails  to  liquefy;  these 
gases  are  burned  under  the  stills ;  then  gasolene  comes 
off  and  is  condensed.  Next  kerosene  or  burning  oil 
comes  over,  and  then  lubricating  oils  and  paraffin.  It 
used  to  be  the  object  to  get  all  the  kerosene  possible, 
and  from  60  to  75  per  cent,  of  Pennsylvania  crude  was 
made  into  kerosene,  but  now  the  demand  is  more  for 
gasolene,  due  to  the  growth  of  the  automobile  industry 
and  other  uses,  such  as  the  internal  combustion  engine. 
By  changing  the  system  of  distillation,  such  as  distill- 
ing with  pressure,  more  gasolene  is  obtained.  It  may 
not  long  be  desirable  to  make  so  much  gasolene,  how- 
ever, as  inventors  are  at  work  on  kerosene  carburetters, 
and  the  writer  has  already  seen  an  automobile  appar- 
ently run  very  nicely  on  nothing  but  kerosene  after 
gasolene  was  used  to  start  it. 

The  writer  has  been  under  the  impression  that  rooms 
in  which  gas  was  burned  required  more  special  ventila- 
tion than  where  electricity  was  used.  From  tests  made 
by  Dr.  Samuel  Eideal,  of  London,  England,  it  appears 


THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT         43 

that  currents  of  air  caused  by  the  lifting  power  of 
heated  gases  produce  enough  ventilation  themselves 
to  take  care  at  least  of  the  carbon  dioxide  and  water 
vapor  formed  in  combustion,  and  that  organic  matter 
from  the  lungs  and  bacterial  content  of  the  air  are 
diminished  by  the  combustion  in  the  flame.  , 

We  have  gone  into  the  subjects  of  gas  and  oil  some- 
what at  length.  "With  reference  to  electric  lighting, 
the  subject  is  not  so  chemical.  Chemistry,  however,  has 
had  a  great  deal  to  do  with  perfecting  the  filaments, 
especially  with  producing  fine  tungsten  that  was  tough 
enough  to  be  drawn  out  into  fine  wire.  The  first  lamps 
were  very  fragile,  but  now  there  is  a  fair  chance  that  a 
lamp  will  last  long  enough  to  be  of  real  value.  Greater 
purity  in  the  metal  renders  it  less  brittle,  and  the  crimp 
of  the  filament  reduces  the  tension  that  tends  to  break 
it  when  hot.  In  spite  of  all  precautions  it  is  still  apt  to 
stretch  and  loosen  the  electrical  contacts  with  the  cop- 
per wire  support,  but  often  a  change  from  a  pendent  to 
an  upright  position,  or  vice  versa,  will  render  it  useful 
again.  Tungsten  is  used  chiefly  because  it  is  a  metal 
that  can  be  heated  by  electrical  resistance  to  an  intense 
white  heat  without  melting,  and  the  higher  a  substance 
is  heated  the  more  light  is  radiated  in  proportion  to 
the  power  applied.  More  efficient  light,  as  regards  the 
power  applied,  can  be  obtained  from  the  tungsten  lamp 
by  the  momentary  application  of  a  greater  than  the 


44  CHEMISTRY  OF  FAMILIAR  THINGS 

normal  current.  This  flash  of  light  can  be  used  for 
photographic  purposes,  due  to  its  great  brilliancy.  An 
ordinary  25-watt  tungsten  lamp  will  produce  20  candle 
power,  while  a  50-watt  carbon  lamp  will  give  only  16 
candle  power. 

RELATION  OF  WATTS  AND  CANDLE  POWEB  OF  RECENT  IMPROVED  TUNG- 
STEN LIGHTS. 


Watts 
10 

Candle  power 
g 

Watts 
60  ... 

Candle  power 
50 

15     . 

12 

100  

90 

25  

20 

250  

240 

40.. 

..32 

400.. 

..400 

The  variation  in  candle  power  due  to  voltage  is  50 
per  cent,  less  than  with  carbon-filament  lamps. 

The  color  of  the  light  of  the  tungsten  lamp  seems  to 
the  writer  to  be  quite  tolerable,  especially  if  the  reading 
lamps  are  not  too  powerful.  For  instance,  this  is  being 
written  with  a  single  15-watt  tungsten  lamp  on  my 
table  and  no  other  light  in  my  small  study,  and  my  eyes 
never  feel  strained,  although  I  write  on  white  paper  but 
avoid  direct  reflection. 

The  Illuminating  Engineering  Society  has  issued  a 
booklet  called  "Light,  its  Use  and  Abuse/'  from  which 
the  following  paragraphs  are  quoted,  which  have  their 
point  largely  in  the  physiological  action  of  the  pupil  or 
opening  of  the  eye  regulated  by  the  iris  and  the  effect  of 
light  upon  the  same.  The  pupil  can  accommodate  itself 
to  the  amount  of  light  directed  toward  the  retina,  if 


THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT          45 

given  a  certain  time  for  the  change,  but  cannot  adapt 
itself  to  sudden  changes  nor  to  the  simultaneous  action 
of  bright  lights  while  endeavoring  to  discern  less  brill- 
iant objects. 

"You  must  get  enough  light  to  see  by,  and,  as  you 
see  things  chiefly  by  the  light  which  they  reflect,  it  is 
evident  that  dark-colored  objects  which  reflect  light 
badly  require  more  light  than  do  light-colored  objects 
to  see  them  comfortably. ' ' 

"Daylight  is  naturally  well  diffused;  but  artificial 
light,  poured  out  as  it  is  from  mere  points  or  narrow 
surfaces,  needs  to  be  tempered  or  softened  by  shades." 

"In  any  artificial  lighting  the  lamps  should  be  so 
well  shaded  that  the  eye  does  not  see  them  directly  nor 
brilliant  reflections  from  them." 

"A  method  frequently  used  for  combining  some  of 
the  advantages  of  both  direct  and  indirect  lighting  is 
to  place  the  lamps  in  a  bowl  of  diffusing  glass.  This 
bowl  reflects  upward  part  of  the  light  as  in  indirect 
lighting  and  lets  through  part  as  in  direct  lighting." 

"No  reflector  ever  increases  the  total  light  that 
streams  out  of  a  lamp:  it  only  puts  the  light  where  it 
is  needed  instead  of  letting  it  go  unguided. " 

' '  Because  dark  walls  absorb  light  strongly  instead  of 
reflecting  it,  they  demand  much  stronger  lamps  for 
sufficient  illumination  than  do  light  walls.  A  very  dark 
wall-paper  or  a  dark  wood  finish  may  require  three  or 


46  CHEMISTRY  OF  FAMILIAR  THINGS 

four  times  as  much  light  as  a  really  light  finish.  Dark 
reds,  greens,  and  browns  reflect  only  10  to  15  per  cent, 
of  the  light  which  falls  on  them.  White,  cream  color, 
and  light  yellowish  tints  may  reflect  over  one-half  the 
light." 

Electricity  is  produced  in  primary  'batteries  by 
chemical  action.  The  batteries  known  as  secondary 
batteries  store  electrical  energy.  As  all  these  proc- 
esses are  chemical,  it  might  be  well  to  consider  them 
briefly.  The  principle  of  the  primary  battery  depends 
upon  there  being  an  electrolyte,  consisting  of  an  acid, 
an  alkali,  or  a  salt,  dissolved  in  water  to  carry  the 
current ;  a  metal  forms  one  pole,  which  tends  to  go  into 
solution  and  in  doing  so  produces  electrical  energy 
which  passes  through  the  conducting  solution  or  electro- 
lyte to  another  metal,  carbon,  or  other  substance,  that 
is  less  energetic  electrically  or  is  electro-negative  to  the 
metal  generating  the  current.  Well-known  elements 
and  compounds  may  be  arranged  in  a  series  in  which 
the  lower  numbered  members  will  generate  current  if 
placed  in  a  cell  containing  dilute  acid  with  the  sub- 
stances of  higher  numbers. 


1.  Magnesium 

7.  Tin 

13.  Silver 

2.  Aluminum 

8.  Lead 

14.  Platinum 

3.  Zinc 

9.  Antimony 

15.  Gold 

4.  Cadmium 

10.  Bismuth 

16.  Carbon 

5.  Iron 

11.  Copper 

17.  Copper  oxide 

6.  Nickel 

12.  Mercury 

J>8.  Lead  dioxide 

THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT         47 

At  the  negative  pole  hydrogen  is  evolved  unless  an 
oxidizing  agent,  such  as  manganese  or  lead  dioxide, 
absorbs  it  by  chemical  action.  The  current  passes  to  the 
outside  circuit  through  the  electro-negative  pole  or 
element,  and  finally  returns  to  the  point  of  formation, 
after  a  drop  in  intensity,  called  voltage.  The  voltage  of 
an  electrical  circuit  is  just  like  the  head  or  pressure  in 
a  water  circuit.  The  normal  voltage  of  a  zinc-sal- 
ammoniac-carbon  dry  cell  is  about  1.5  volts  when  fresh 
and  1.0  volt  or  less  when  run  down.  The  amount  of 
current  passed  is  measured  by  a  unit  called  the  ampere. 
The  amperage  of  a  cell  depends  upon  the  resistance, 
such  as  the  winding  of  the  electro-magnet  of  a  bell  or 
the  filament  of  a  lamp.  The  more  the  resistance  the 
less  the  current.  The  types  of  primary  batteries  prob- 
ably most  used  are  (1)  zinc-carbon  cells  with  ammonium 
chloride  (sal  ammoniac)  solution  as  the  electrolyte. 
These  generally  are  filled  with  absorbent  material  to 
keep  the  liquid  from  spilling  when  not  kept  upright,  and 
the  carbon  is  surrounded  by  manganese  dioxide  and 
graphite  to  absorb  the  hydrogen  that  would  otherwise 
pass  off.  These  cells  generally  give  out  by  alteration  of 
the  electrolyte,  and  a  little  additional  life  may  be  given 
then  by  putting  in  some  fresh  ammoniac  solution. 
They  are  called  dry  cells. 

Another  cell  much  used  is  (2)  the  Edison-Lalande, 
which  consists  of  zinc  rods  as  generating  elements,  an 


48  CHEMISTRY  OF  FAMILIAR  THINGS] 

electrolyte  of  sodium  hydroxide,  and  copper-oxide 
plates.  These  plates  are  black  when  fresh,  but  the 
hydrogen  which  they  absorb  turns  them  red  from  for- 
mation of  metallic  copper.  In  handling  this  cell  it  is 
well  to  be  careful  about  getting  sodium  hydroxide  solu- 
tion on  the  hands,  as  it  is  very  caustic.  The  voltage 
of  this  cell  is  low,  but  it  lasts  a  long  time  when  not  in 
use  or  on  open  circuit.  Other  cells  are  used  for  some 
special  purposes,  such  as  telegraphy.  For  household 
use  where  one  has  an  alternating  current,  so-called 
"toy"  transformers  are  useful  for  bell  ringing,  as 
they  never  go  dry  or  play  out. 

Secondary  cells  or  storage  batteries  are  generally 
made  up  of  spongy  lead  plates  as  negative  poles,  diluted 
sulphuric  acid  as  electrolyte  and  lead-peroxide  plates 
as  the  positive  pole.  They  generate  current  by  the 
union  of  lead  with  the  sulphuric  acid  and  the  action  of 
hydrogen  on  peroxide  of  lead.  Current  is  obtainable 
when  fully  charged  to  quite  a  considerable  extent,  but 
gradually  the  intensity  diminishes,  as  is  indicated  by  a 
lowering  of  the  voltage.  This  is  largely  accounted  for 
by  the  union  of  sulphuric  acid  with  lead  oxide  at  both 
poles.  This  makes  the  electrolyte  less  of  a  conductor 
(more  resistance)  due  to  loss  of  acid,  and  there  is  more 
resistance  to  the  passage  of  the  current  at  the  poles  due 
to  lead  sulphate  being  present  and  less  active  matter. 
The  Edison  storage  battery  consists  of  iron  and  nickel 


THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT          49 

peroxide  with  an  alkaline  solution  as  an  electrolyte. 
This  cell  costs  more  for  the  power  generated  or  stored, 
but  is  lighter  for  the  same  power  and  therefore  is  useful 
for  portable  purposes. 

Acetylene  gas  is  generated  by  adding  water  to  cal- 
cium carbide,  an  electric-furnace  product  made  by 
heating  coke  and  lime.  This  form  of  illumination  is 
used  in  detached  installations  and  the  light  is  very 
intense  and  concentrated;  therefore,  the  flames  should 
always  be  seen  through  ground  glass  or  glass  that  has 
been  treated,  to  absorb  the  most  irritating  rays.  Alco- 
hol is  used  for  lighting  in  Europe,  but  is  rather  ex- 
pensive for  use  in  this  country.  It  must  be  used  in  con- 
nection with  mantles,  as  it  otherwise  gives  only  a  bluish, 
but  hot,  flame. 

Mantles  used  for  gas  illumination  are  composed  of 
oxides  of  rare  elements.  They  are  generally  a  mixture 
of  ninety-nine  per  cent,  thorium  oxide  with  one  per 
cent,  of  cerium  oxide.  After  the  protecting  substance 
(collodion)  has  been  burned  off,  they  are  mechanically 
weak,  and  should  be  protected  from  outside  influences, 
such  as  matches  and  tapers  poked  into  them  for  light- 
ing and  knocks  or  vibrations.  When  taken  care  of  they 
last  a  long  time.  Those  made  from  artificial  silk  are 
relatively  strong. 

Matches  in  this  country  are  mostly  of  two  kinds, — 
the  double  dip  or  tipped,  strike-anywhere  match  and  the 
4 


50  CHEMISTRY  OF  FAMILIAR  THINGS 

safety  match  which  must  be  struck  on  the  box.  The 
older  form  of  strike-anywhere  match,  with  no  tip  and 
made  with  white  phosphorus,  is  no  longer  used.  For 
one  thing,  it  is  no  longer  legal  to  use  yellow  phosphorus, 
due  to  the  danger  of  the  operatives  getting  "phossy- 
jaw."  Phosphorus  sesquisulphide  is  now  used  in 
strike-anywhere  matches  or  in  the  very  tips  of  them. 
This  new  substance  seems  to  the  writer,  who  has  visited 
match  works  frequently,  to  be  a  cure  worse  than  the 
disease.  Phosphorus  sesquisulphide  may  not  produce 
necrosis  (phossy-jaw),  but  it  is  very  hard  on  the  eyes 
of  those  who  make  it,  and  even  the  match  makers  have 
complained  of  it.  It  is  highly  probable  that  in  a  few 
years  legislation  will  take  hold  of  the  matter  again,  and 
direct  that  only  red  phosphorus  be  used,  as  in  safety 
matches. 

Matches  are  essentially  mixtures  of  some  form  of 
phosphorus,  potassium  chlorate  or  oxidized  red  lead, 
powdered  glass,  zinc  oxide,  rosin,  glue  and  coloring 
matter.  In  safety  matches  part  of  the  composition 
(the  red  phosphorus)  is  on  the  box,  so  that  the  matches 
themselves  will  not  ignite  without  the  boxes.  Eecent 
improvements  in  matches  include  the  impregnation  of 
the  stem  of  the  match  with  a  fire-resisting  chemical, 
such  as  sulphate  of  ammonia,  so  that  sparks  will  not  be 
retained  by  a  supposed  burned-out  match-stick  and 
start  up  a  blaze.  People  can  then  throw  them  into  the 


THE  CHEMISTRY  AND  PRODUCTION  OF  LIGHT         51 

waste-paper  baskets  with  impunity!  Paraffin  applied 
to  the  splint  before  the  composition  is  added  holds  the 
light  and  causes  the  wood  to  burn  a  reasonable  time. 

There  are  several  other  ways  in  vogue  for  striking 
fire  other  than  the  use  of  matches.  The  older  of  these  is 
with  a  small  platinum  sponge  or  platinum  black,  which 
when  dipped  into  wood  alcohol  and  exposed  to  the  air 
causes  the  ignition  of  the  wood  alcohol.  This  is  an  ex- 
ample of  catalytic  action.  The  platinum  seems  to  act 
by  giving  great  surface  to  the  alcohol  and  condensing 
air  or  oxygen  in  contact  with  it,  which  causes  instant 
oxidation,  heat,  and  consequent  flame.  The  other  and 
more  recent  method  is  to  draw  a  pencil  point  of  cerium- 
iron  alloy  over  a  piece  of  a  file,  which  causes  a  volumi- 
nous sparking,  and  these  sparks  are  used  to  light  gas 
or  gasolene  vapor.  Cerium  seems  to  be  oxidized  by 
the  heat  of  friction  in  the  presence  of  air,  and  as  it 
momentarily  burns  by  oxidation  it  gives  a  flame.  It 
has  recently  been  found  that  uranium  carbide  is  a  pyro- 
phoric  substance  like  cerium  alloy. 


CHAPTEB  V 

HEAT,   COMBUSTION,   AND   INSULATION 

WE  NEED  a  regular  supply  of  the  manifestation  of 
energy  called  heat  very  nearly  as  much  as  we  need  a 
regular  supply  of  air,  and  in  a  large  part  of  the  world 
artificially  created  heat  is  a  very  vital  necessity.  The 
more  enlightened  people  are,  the  more  heat  they  need 
for  comfort  in  countries  that  have  winter.  We  can  keep 
warm  enough  for  nature *s  requirements  by  clothing 
alone,  which  means  the  shutting  in  and  utilizing  the 
heat  generated  by  the  combustion  of  our  food,  but  most 
of  us  want  greater  freedom  of  action,  and  therefore 
use  a  great  deal  of  fuel  to  keep  our  houses  temperate 
instead  of  being  bundled  in  clothing  in  winter  time. 
Too  much  clothing  interferes  also  with  the  respira- 
tion through  the  skin,  which  undoubtedly  is  a  vital 
necessity. 

At  low  temperatures,  without  the  special  precaution 
of  heavy  clothing  or  heated  shelter,  we  are  unable  to 
create  heat  fast  enough  to  maintain  the  bodily  func- 
tions, no  matter  how  much  we  eat,  unless  we  are  taking 
violent  exercise,  when  more  heat  would  be  created,  due 
to  active  tissue  consumption.  Unless  a  person  is  in 
energetic  motion  he  should  not  tolerate  a  sense  of  cold  if 

52 


HEAT,  COMBUSTION,  AND  INSULATION  53 

he  can  prevent  it,  although  parts  of  the  body  may  be 
cold  if  the  trunk  is  warm. 

We  notice  heat  directly  by  our  sense  of  touch. 
Through  a  relatively  narrow  range  we  can  tell  to  what 
extent  heat  passes  from  us  to  an  object  if  it  is  cold  or 
from  the  object  to  us  if  it  is  warm,  and  grade  these 
sensations  in  a  rough  series.  We  have  all  come  in 
contact  with  colder  and  hotter  substances  than  were 
comfortable,  and  few  repetitions  have  been  necessary 
to  convince  us  that  better  means  of  measuring  tempera- 
tures should  be  used  than  the  sense  of  touch.  We  have 
adopted  instruments  for  registration  of  heat  which  we 
call  thermometers,  on  which  differences  of  temperature 
are  registered  in  degrees  due  to  the  expansion  of  mer- 
cury in  proportion  to  the  temperature.  The  two  chief 
systems  are  the  Centigrade  (or  Celsius)  and  the 
Fahrenheit.  The  former  is  the  more  rational  and  is 
used  in  all  scientific  work  and  generally  on  the  continent 
of  Europe.  We  have  inherited  from  England  the  in- 
ferior unit,  or  Fahrenheit  degree.  The  units  of  length, 
volume,  and  temperature,  which  have  come  to  us  from 
the  mother  country,  are  all  inferior  to  the  continental 
or  decimal  system  of  units.  It  is  something  to  be  thank- 
ful for  that  we  did  not  adopt  the  English  monetary 
unit.  The  two  most  easily  determined  points  with  refer- 
ence to  heat  are  the  melting  point  of  ice  and  the  boil- 
ing point  of  water  at  the  sea  level. 


54  CHEMISTRY  OF  FAMILIAR  THINGS 

COMPARISON  OF  TEMPERATURES.* 

Melting  point  Boiling  point 
of  ice  of  water 

Fahrenheit  (F.)   32°  212° 

Centigrade  (C.)    0°  100° 

Science  teaches  us  that  the  molecules  of  all  sub- 
stances are  in  vibration,  due  to  the  heat  they  possess, 
and  the  higher  the  temperature  the  greater  the  move- 
ment and  consequent  expansion  of  liquids  (such  as 
mercury)  and  some  solids.  By  calculation  it  has  been 
deduced  that  at  a  temperature  273°  below  zero  C.,  all 
such  motion  would  cease,  and  this  is  called  the  absolute 
zero.  This  point  is  the  basis  of  calculations  as  to  the 
volumes  of  gases,  but  is  of  no  significance  in  ordinary 
heat  measurements.  Artificial  means  of  creating  cold, 
however,  have  gone  almost  this  far  in  special  research 
work,  as  Ohmes  has  obtained  — 272°  C.  by  evaporating 
liquid  helium. 

Ordinarily  heat  is  considered  as  coming  from  three 
sources :  the  sun,  chemical  combustion,  and  mechanical 
means.  In  the  last  analysis,  however,  there  are  really 
only  two, — the  heat  of  the  sun  and  chemical  heat,  as 
mechanical  heat  comes  from  the  combustion  of  coal,  oil, 
etc.  (chemical  source),  water-power  or  the  wind. 
The  last  two  are  due  to  the  solar  heat  exercised  in 

*It  will  thus  be  seen  that  180  degrees  F.  =  100  degrees  C.  To 

convert  Fahrenheit  to  Centigrade,   subtract  32,  multiply  by  100,  and 

divide  180.     To  convert  Centigrade  into  Fahrenheit,  multiply  by  180, 
divide  by  100,  and  then  add  32. 


HEAT,  COMBUSTION,  AND  INSULATION  55 

elevating  the  water  by  evaporation  and  causing  the 
changes  in  temperature  which  produce  differences  in 
density  and  create  air  currents. 

The  sun  is  mostly  in  the  vaporous  condition,  at  a 
temperature  of  about  6000°  C.,  and  is  a  sphere  because 
of  its  force  of  gravity  or  cohesion.  The  radiations 
from  the  sun  are  so  intense  that  a  great  deal  of  light  is 
given  off,  as  well  as  heat.  As  there  is  only  a  thin  coat- 
ing of  atmosphere  around  the  earth  and  in  the  neighbor- 
hood of  the  sun,  it  is  evident  that  the  heat  and  light  are 
transmitted  through  the  vacuous  space  between  the  sun 
and  earth  by  reason  of  the  vibratory  motion  and  not 
by  conduction.  The  intervening  vacuum  is  not  heated. 

Heat  from  chemical  sources  is  well  known  to  us, 
but  it  is  not  very  generally  appreciated  that  the  source 
is  chemical.  In  the  first  place,  all  the  heat  of  the  body 
is  chemical  heat.  The  food  is  the  fuel  for  this  low-tem- 
perature heating  system.  Probably  the  little  fires  all 
over  the  body  would  be  rather  hot  if  the  blood  did  not 
circulate  by  means  of  a  pump  designed  for  the  purpose, 
the  blood  carrying  off  the  heat  as  fast  as  formed.  Coal 
fires  are  the  prevalent  means  of  creating  .artificial  heat, 
but  it  does  not  make  any  difference  in  principle  if  the 
fuel  be  wood  or  lignite,  peat  or  coal,  oil  or  gas,  as  the 
combustible  contains  carbon  and  hydrogen,  which  burn 
with  air  to  produce  carbon  dioxide  and  water. 


56 


CHEMISTRY  OF  FAMILIAR  THINGS 


TABLE  OF  FUELS. 


Fuel 
Cellulose 

Hydrogen 

6  2 

Carbon 

44  5 

Oxygen  and 
nitrogen 

44.3 

Ash 

Fuel  value  in 
inB.T.U.perlb. 

7,500 

Wood  
Peat  

6.0 
4.5-6.8 

50. 
50-64. 

44.0 
28.6-44. 

7,200-  7,500 
9,000-10,800 

Lignite 

5 

60-75. 

20.  -35. 

10,800-12,600 

Soft  coal  

4.  -6. 

75-90 

5.5-15 

5-10 

13,500-15,000 

Anthracite 

1     -2 

90-95 

3. 

10-20 

12,500-14,000 

Gasolene 

.  .    variable 

about  21,000 

Kerosene.  .  .  . 

« 

"      20,000 

Benzol 

8  0 

92  0 

18,450 

Crude  oil.  .  , 

.  .  variable 

about  19,000 

The  practical  utilization  of  heat,  whether  in  steam 
boilers  for  factories  or  in  hot-air,  steam  or  hot-water 
furnaces  of  houses,  is  at  best  inefficient.  When  com- 
bustion takes  place  gases  are  formed,  first,  either  by 
distillation  from  the  fuel  itself  or  by  the  partial  com- 
bustion with  oxygen.  If  by  distillation,  hydro-carbons 
are  largely  formed.  If  by  the  partial  combustion  by 
air,  carbon  monoxide  is  formed.  There  is  generally  a 
composite  gas  containing  both  these  elements  first 
formed,  which  burns  above  the  £uel  bed  to  carbon 
dioxide  and  water  vapor.  The  gaseous  products  contain 
a  large  portion  of  the  heat,  and  some  of  this  is  extracted 
for  useful  purposes  by  having  plenty  of  surface  in  the 
parts  of  the  furnaces  where  the  heat  may  be  absorbed, 
but  a  great  deal  goes  up  the  flue  and  only  serves  a  use- 
ful purpose  in  causing  a  draught,  which  draws  in  the 
air  under  the  grate  bars.  When  less  heat  is  required, 
however,  some  air  is  drawn  in  above  the  fuel  bed  to 
cut  down  the  action  of  air  through  the  fuel  and  to  fully 


HEAT,  COMBUSTION,  AND  INSULATION  57 

consume  any  gases  that  have  distilled  and  not  otherwise 
had  enough  air  for  combustion.  Heat  is  lost  by  radia- 
tion at  the  grate  bars  and  around  the  furnace  or  boiler. 
In  well-arranged  steam  boilers  or  hot-water  heaters, 
the  water  to  be  heated  nearly  surrounds  the  fire  bed 
and  the  space  above  it,  and  in  some  cases,  as  in  marine 
boilers,  comes  below  the  space  under  the  grate  bars,  so 
as  to  take  up  any  stray  heat.  To  take  up  all  the  heat 
possible  most  boilers  have  a  tubular  surface  filled  with 
water  in  the  path  of  the  burning  gases.  Sufficient  heat 
should  be  supplied  to  every  room  in  a  house,  etc.,  to 
allow  of  a  complete  change  of  air  twice  an  hour. 

Everybody  is  acquainted  with  the  fact  that  on  a 
cloudy  or  rainy  day  fires  do  not  draw  well.  This  is  due 
to  low  barometric  pressure,  which  does  not  give  suffi- 
cient difference  in  weight  between  a  column  of  air,  the 
height  of  the  chimney,  and  this  column  of  flue  gases. 
On  a  clear  day  the  hot  flue  gases  are  very  much  lighter 
and  the  weight  of  the  atmosphere  pushing  at  the  grate 
bars  is  notably  greater  than  that  at  the  top  of  the 
chimney.  This  creates  a  good  draught.  Wind  causes 
a  suction,  as  a  rule,  at  the  chimney  top,  and  some  con- 
trivances assist  in  this  matter,  but  most  of  them,  espe- 
cially those  that  revolve,  become  corroded  by  acid  gases 
from  coal  tar  and  acid  from  burning  wood  and  get  out 
of  order  very  easily.  This  suction  effect  is  mechanical. 

To  obtain  the  most  efficient  service  from  a  domestic 


58  CHEMISTRY  OF  FAMILIAR  THINGS 

heater,  it  is  best  to  use  coal  of  such  size  that  the  fire  does 
not  die  out  around  the  sides  and  produce  an  insulating 
layer.  Then  it  is  well  to  have  a  large  body  of  glowing 
coals  with  little  draught  after  the  fire  is  well  started. 
With  a  fire  banked  high  in  the  centre  and  lower  on  the 
sides  one  gets  the  greatest  amount  of  radiating  surface 
from  the  fuel  and  exposes  the  sides  in  a  hot-water  or 
steam  generator  to  hot  gases  rather  than  to  ashes  or 
to  coal  that  is  not  burning.  For  economical  reasons 
it  is  not  well  to  rake  the  fire  very  thoroughly,  as  a  layer 
of  ashes  on  the  grate  bars  acts  as  an  insulation,  and 
very  little  heat  is  radiated  downward.  One  should  be 
able  to  hold  his  hand  under  the  grate  bars  with  com- 
fort, unless  live  coals  have  dropped  in  raking.  Very 
few  of  these  should  be  raked  out,  of  course.  Where 
there  are  water  tubes  or  pipes,  they  should  be  cleaned 
of  soot  often,  as  that  material  is  a  good  insulation  in 
a  bad  place.  All  the  insulation  ought  to  be  around  the 
outside  of  the  boiler  and  not  inside. 

Another  method  of  creating  heat  is  by  mechanical 
means, — friction.  A  German  physicist,  Robert  Mayer, 
found  a  value  that  constituted  the  mechanical  equivalent 
of  heat.  Expenditure  of  mechanical  forces  always 
results  in  a  definite  amount  of  heat.  Friction  is  the 
term  given  to  the  resistance  to  motion  that  causes  heat. 
Sometimes  mechanical  force  produces  electricity,  but 
this  finally  goes  into  heat.  All  force  goes  into  a  corre- 


HEAT,  COMBUSTION,  AND  INSULATION  59 

spending  amount  of  heat,  and  all  heat  produces  its 
equivalent  in  force,  although  it  works  in  a  roundabout 
way  in  nature  by  causing  the  growth  of  plants,  thus 
producing  grains  and  grass  for  animal  consumption 
and,  in  time  gone  by  and  to  some  extent  now,  coal  and 
oil.  Any  of  this  energy  in  coal  or  food  that  is  not  con- 
sumed to  create  work  is  still  potential  or  stored  energy. 
The  fact  is  it  would  be  hard  to  know  how  the  total  heat 
of  the  universe  could  change  very  much,  as  for  any 
planet  that  was  cooling  off,  another  must  be  absorbing 
the  heat  in  some  way. 

Heat  moves  in  substances,  as  electricity  does  in 
wires.  Heat  flows  through  metals  best,  moderately  well 
in  water,  and  to  a  lesser  extent  in  air.  In  water  and  air 
it  moves  chiefly  by  currents  called  convection  currents. 
Some  people  think  cold  radiates ;  that  a  cold  substance 
like  a  window-pane  sends  off  cold.  It  seems  to  do  so 
only  by  absorbing  heat.  For  heat  to  move  best  in  water 
or  air,  it  must  rise  and  circulate.  It  returns  when 
cooled.  Heat  causes  the  particles  of  a  body  to  vibrate 
more  rapidly  and  this  tends  to  cause  a  more  fluid  state. 
If  one  heats  ice,  water  is  obtained,  which  is  fluid  due  to 
the  mobility  of  its  particles,  and  when  heated  still 
further  all  tendency  to  be  held  together  is  lost,  as  the 
motion  of  the  particles  overcomes  all  force  of  cohesion, 
and  steam  results.  Iron  becomes  liquid  and  at  a  white 
heat  it  vaporizes.  At  the  heat  of  the  electric  arc  all 


60  CHEMISTRY  OF  FAMILIAR  THINGS 

known  metals  vaporize,  and  even  carbon  is  slowly 
vaporized. 

When  ice  melts  it  takes  on  a  quantity  of  heat  called 
latent  heat' of  fusion.  When  it  freezes  again,  this  latent 
heat  is  given  off,  which  slows  down  the  freezing  until 
this  heat  can  be  absorbed.  There  is  thus  a  check  on 
thawing  and  a  check  on  freezing.  If  it  were  not  for  this, 
a  lake  or  river  would  freeze  to  the  bottom  as  soon  as  it 
began  to  freeze.  Similarly,  when  water  or  any  liquid 
is  converted  into  a  gas,  there  is  absorbed  quite  a  quan- 
tity of  heat  called  latent  heat  of  vaporisation.  Here 
again  the  wonderful  provision  of  nature  protects  the 
food  that  is  being  cooked  by  not  permitting  all  the  boil- 
ing water  to  go  into  steam  at  once,  but  provides  for  so 
much  heat  being  absorbed  that  it  takes  a  relatively  long 
time  to  boil  off  a  quantity  of  water. 

One  of  the  most  important  conceptions  in  connection 
with  heat  is  that  of  insulation.  Our  clothing  is  insula- 
tion to  keep  in  heat,  so  are  bedclothes  and  the  walls 
of  houses.  The  fur  on  animals,  the  feathers  of  birds,  and 
the  blubber  of  whales  are  for  purposes  of  insulation  or 
keeping  in  body  heat.  The  way  most  of  these  sub- 
stances act  is  by  shutting  in  air  in  pockets  so  there  are 
no  currents.  Thus  air  makes  a  good  insulator  or  non- 
conductor. It  is  called  dead  air  in  these  cases.  Massive 
silica  acts  as  a  good  conductor,  but  finely  powdered 
silica  is  an  insulator;  finely  powdered  magnesia,  asbes- 


HEAT,  COMBUSTION,  AND  INSULATION  61 

tos,  carbon,  dry  wood,  and  cork  are  good  insulators  be- 
cause of  the  fine  pores  or  dead-air  spaces  they  contain. 

When  a  person  builds  a  house  he  should  be  informed 
of  the  possible  insulating  qualities  of  the  walls,  the 
down-stairs  floors,  the  ceilings  under  the  roof,  etc.,  so 
as  to  have  it  warm  and  yet  allow  of  the  requisite  fresh 
air  to  enter  in  cold  weather  without  burning  undue  fuel. 
The  writer  has  noticed  the  great  difference  in  tem- 
perature on  a  very  cold  day  on  touching  the  outside  wall 
in  his  kitchen  (18  inches  stone  laid  in  deep  mortar  with  3 
outside  coats  of  plaster  and  inside  laths  and  plaster) 
with  one  hand  and  the  wall  of  the  laundry  with  the  other 
(which  is  of  frame,  although  of  good  construction,  with, 
plaster  outside  and  inside).  The  difference  on  a  cold 
day  was  remarkable,  and  all  in  favor  of  the  stone  wall. 
There  is  not  space  here  for  figures  on  insulation,  but 
abundant  data  may  be  found. 

Other  examples  of  insulation  are  noticed.  In  heat- 
ing a  pan  containing  water,  the  flame  does  not  seem  to 
touch  the  pan.  In  fact,  it  does  not,  but  is  so  chilled  that 
there  is  only  a  layer  of  cooled  gases  from  the  flame 
touching  the  pan,  which  tends  to  insulate  it  from  the 
flame.  The  writer  has  often  wondered  why  the  same 
amount  of  gas  in  a  quiet  burner  did  not  give  the  effec- 
tive heat  given  by  a  blast  lamp.  The  force  of  the  blast 
drives  away  the  insulating  film  and  forces  the  hot  flame 
right  up  to  the  object  being  heated.  If  a  drop  of  water 


62  CHEMISTRY  OF  FAMILIAR  THINGS 

falls  on  a  red-hot  stove  plate,  it  is  seen  to  spin  around 
rapidly,  but  remains  for  some  time,  while  if  the  plate 
were  only  moderately  hot,  the  water  would  flatten  out 
and  evaporate.  This  is  called  spheroidal  state,  and  is 
caused  by  the  insulating  effect  of  the  steam  between 
the  globule  of  water  and  the  hot  plate. 

People  are  generally  familiar  with  modern  improve- 
ments in  heating  of  houses  and  other  buildings.  Some 
of  the  larger  recent  improvements  in  the  utilization  of 
heat  may  be  here  referred  to.  Hundreds  of  thousands 
of  horse-power  used  to  go  to  waste  in  the  shape  of 
combustible  gas  from  blast  furnaces.  Almost  every 
one  has  seen  large  volumes  of  burning  gases  ejected 
from  the  tops  of  such  furnaces  when  passing  in  a  train 
or  otherwise ;  and  at  night  it  has  been  a  beautiful  sight 
the  way  the  whole  neighborhood  is  illuminated  by  a  red 
glow  from  this  periodic  occurrence.  Now  the  manu- 
facturers of  iron  are  using  these  gases  to  create  power 
in  gas-engines  and  soon  these  works  will  be  less  pictur- 
esque at  night,  but  all  will  benefit  by  the  saving,  as  we 
do  in  all  large  manufacturing  economies. 

The  greatest  advance  in  heating  has  been  in  the 
electric  furnaces  that  make  graphite,  calcium  carbide, 
aluminum,  tool  steel,  phosphorus,  etc.  Some  of  these 
furnaces  use  several  thousand  horse-power  or  kilo- 
watts. A  kilowatt  is  about  one-third  more  power  than 
a  horse-power.  The  sources  of  electric  power  in  this 


HEAT,  COMBUSTION,  AND  INSULATION  63 

country  are  water  power,  anthracite  coal  waste  or  culm, 
blast-furnace  gases,  producer  gas  or  coal-fired  boilers. 

At  one  time  there  was  a  very  large  piling  up  of  fine 
siftings  of  anthracite  coal,  forming  enormous  culm 
piles.  A  large  part  of  this  former  discard  has  of  recent 
years  been  resieved  and  used  as  buckwheat  and  rice 
grades  for  use  in  steam  boilers.  For  household  use  they 
have  been  impracticable,  except  with  automatic  feed- 
ing tubes  in  the  furnaces  or  boilers,  in  which  case  their 
consumption  has  been  possible.  Under  present  condi- 
tions the  amount  of  culm  formed  is  not  great,  but,  as  it 
is,  it  lends  itself  to  a  new  and  useful  industry, — that  of 
the  manufacture  of  coal  briquettes  (coalettes).  Fuel  in 
this  form  may  be  practically  as  good  as  in  assorted 
sizes,  as  the  binder  can  have  burning  properties  itself, 
and  the  coal  may  hold  together  in  lumps,  practically 
until  consumed.  It  is,  of  course,  sold  for  less  than  the 
prices  of  domestic  sizes  to  make  it  interesting  to  the 
householder. 

There  was  a  period  in  this  country's  history,  that 
has  in  fact  extended  until  about  the  beginning  of  this 
century,  when  there  was  very  little  attention  given  to 
saving  materials,  heat,  power,  or  labor.  The  effort  to 
save  labor  came  first,  especially  as  labor  began  to 
demand  more  compensation;  then  power  was  econo- 
mized by  putting  in  individual  motors,  economical 
boilers,  water-power  plants,  etc.  During  the  last  decade 


64  CHEMISTRY  OF  FAMILIAR  THINGS 

there  lias  been  very  constant  effort  to  save  waste 
materials  or  by-products,  and  much  can  yet  be  done. 
Probably  what  is  most  requisite  now  is  a  complete 
checking  up  by  experts  of  all  the  factors  of  labor, 
machinery,  waste  materials,  and  power.  It  will  require 
a  chemical  engineer  of  the  best  training  and  aptitude. 
He  will  be  the  final  efficiency  engineer. 

Some  time  ago  the  writer's  father  read  a  paper  on 
Conservation  in  Chemistry,  in  which  he  spoke  of  three 
periods  in  this  country's  history.  The  first  he  called 
Exploration,  the  second  Exploitation,  and  the  third  he 
said  was  just  dawning  and  called  it  Conservation. 


CHAPTER  VI 

AIR,   OXIDATION,   AND  VENTILATION 

AIR,  or  "the  atmosphere,"  surrounds  the  earth  as 
a  gaseous  covering  which,  because  of  its  weight  and 
compressibility,  is  densest  at  the  surface  and  of  vanish- 
ing quantity  at  distances  of  from  50  to  200  miles  above 
the  earth.  It  is  so  rare  at  50  miles  that  it  ceases  to  affect 
light  rays. 

It  can  be  experimentally  shown  that  air  has  weight 
by  weighing  on  a  balance  and  in  other  ways.  If  a  pipe, 
open  at  the  bottom  and  dipping  into  water,  be  ex- 
hausted at  its  upper  end  through  an  opening  and  then 
the  opening  be  closed,  it  will  be  seen  that  water  rises  to 
fill  the  place  of  the  air  extracted.  It  has  been  found  that 
water  will  rise  34  feet  in  this  way.  As  the  lower  end 
of  the  tube  dips  into  water  and  the  water  in  the  vessel 
is  exposed  to  the  outside  air,  the  weight  of  the  atmos- 
phere must  just  balance  this  column  of  water  of  about 
34  feet  in  height.  As  mercury  is  many  times  heavier 
than  water,  it  does  not  take  as  high  a  column  of  mer- 
cury to  balance  the  pressure  of  the  air;  in  fact,  about 
30  inches  of  mercury  are  as  heavy  as  a  column  of  water 
of  34  feet,  or  one  of  air  as  high  as  the  atmosphere  ex- 

5  65 


66 


CHEMISTRY  OF  FAMILIAR  THINGS 


tends.    Because  of  mercury  making  a  more  practical 
column  to  measure  the   atmospheric  pressure  than 
water,  it  is  thus  used  in  instruments  known  as  barom- 
($\  eters.    The  mercury  barometer,  in  its 

simplest  form,  is  a  glass  tube  somewhat 
over  30  inches  long  and  closed  at  one 
end.  It  is  first  filled  with  mercury  and 
then  inverted  over  a  cup  containing  mer- 
cury. The  mercury  in  the  tube  drops  a 
little,  leaving  a  vacuum  at  the  top,  and 
the  distance  between  the  top  level  and 
the  mercury  in  the  cup  is  equal  to  the 
pressure  of  the  atmosphere,  or  about  30 
inches  (equal  to  760  millimetres  at  the 
sea-level)  on  a  clear  day.  In  stormy 
weather  it  drops  an  inch  or  a  little  more, 
and  at  higher  levels,  such  as  in  moun- 
tainous or  plateau  regions,  it  is  less. 
This  lowering  of  the  barometric  press- 
ure allows  of  the  boiling  of  water  at 
lower  temperatures  than  212°  F.  (100° 
C.),  and  on  very  high  mountains  it  boils 
as  low  as  180°  F.  This  vacuum  in  the 
baromete1?. '  barometer  tube  is  known  as  the  Torri- 
cellian vacuum,  after  Torricelli,  who  was  the  first  im- 
portant investigator  working  on  the  properties  of  the 
air  in  the  seventeenth  century.  Lavoisier  and  Cav- 


AIR,  OXIDATION,  AND  VENTILATION  67 

endish,  as  we  have  seen,  showed  the  true  composi- 
tion of  the  air  in  the  latter  part  of  the  eighteenth 
century.  Air  is  over  14  times  as  heavy  as  hydrogen, 
and  water  is  800  times  as  heavy  as  air. 

Air  is  remarkably  uniform  in  composition,  due  to 
the  fact  that  plants  are  great  feeders  on  carbon  dioxide 
that  people  and  lower  animals  produce  in  large  quan- 
tities. Because  we  know  a  thing  happens  it  can  gen- 
erally be  explained.  Wherever  people  are,  there  are 
plants  to  consume  the  human  and  animal  output  of 
carbon  dioxide,  but  the  plants  fail  to  consume  all  that 
is  in  the  air,  as  their  decaying  vegetation  in  largest 
part  ferments  or  rots,  giving  off  again  what  they  have 
held  for  a  season  or  for  a  longer  period.  There  must 
at  one  time  have  been  much  larger  quantities  of  car- 
bon dioxide  in  the  atmosphere,  as  a  great  deal  of  the 
surface  and  near  surface  rocks  are  carbonates,  and 
now  take  very  little  part  in  the  carbon  dioxide  cycle. 
When  there  was  much  more  carbon  dioxide  in  the  air 
plants  grew  more  profusely,  as  seems  to  have  been 
the  case  in  the  coal  age.  The  presence  of  carbon  di- 
oxide in  the  air  can  be  demonstrated  by  blowing  air 
through  a  tube  into  some  clear  lime  water.  The  liquid 
at  once  becomes  cloudy  or  milky,  from  carbon  dioxide. 
The  white  deposit1  that  forms  in  the  lime  water  that 
is  purchased  from  the  drug  store,  when  it  is  uncorked 

C0a  —  CaC03  +  H20. 


68  CHEMISTRY  OF  FAMILIAR  THINGS 

a  few  times  and  kept  a  while,  is  due  to  this  formation 
of  calcium  carbonate.  Sometimes  it  is  very  important 
to  ascertain  whether  air  in  wells,  brewing  vats,  etc., 
is  contaminated  seriously  with  carbon  dioxide.  To  test 
the  matter  a  lighted  candle  is  lowered  before  men  ven- 
ture in.  If  the  candle  is  extinguished  the  air  is  cer- 
tainly contaminated,  and  pure  air  must  be  introduced 
before  it  is  safe  to  venture  into  such  places. 

The  important  constituents  of  the  air  occur  in  the 
following  proportions: 

By  volume  By  weight 

Nitrogen    78.06  per  cent.  75.50  per  cent. 

Oxygen 21.00  per  cent.  123.20  per  cent. 

Argon     0.91  per  cent.  1.25  per  cent. 

Carbon  dioxide 0.03  per  cent.  0.05  per  cent. 

There  is,  in  addition,  a  variable  percentage  of  mois- 
ture, as  vapor,  in  the  air,  and  very  small  quantities  of 
"helium,  neon,  krypton,  and  xenon.  Besides  these  ele- 
ments there  are  nearly  always  in  the  air  traces  of  hydro- 
gen, ammonia,  nitric  and  nitrous  acids,  ozone,  sulphur 
gases,  and  organic  impurities  such  as  are  supposed  to 
be  exhaled  by  people.  The  burning  of  coal  gives  off 
sulphur  dioxide  gas.  It  has  been  estimated  that  1300 
tons  of  sulphur  dioxide  pass  into  the  atmosphere  in 
New  York  City  every  day  from  the  combustion  of  coal. 

Nitrogen  (N)  is  an  inert  gas,  and  its  consideration 
includes  argon,  which  was  long  unknown  and  included 
in  all  analyses  with  nitrogen,  and,  in  fact,  even  now  few 


AIR,  OXIDATION,  AND  VENTILATION  69 

investigators  attempt  to  separate  the  two  gases  when 
they  analyze  air.  The  other  recently  discovered  gases 
are  small  in  amount,  much  like  nitrogen,  and  have  no 
special  influence  that  we  know  of,  although  they  may  in 
time  be  found  to  perform  some  special  functions.  They 
may  have  come  from  the  degradation  of  elements  such 
as  radium,  some  of  which  may  no  longer  exist,  at  least 
near  the  earth's  surface. 

Water  is  a  quite  variable  constituent  of  the  air. 
When  the  air  is  saturated  with  water  at  any  tempera- 
ture, it  is  said  to  be  at  the  dew-point,  and  the  colder  the 
air  becomes,  the  more  water  is  precipitated  in  nature, 
as  rain.  Warm  currents  of  air  can,  of  course,  carry 
much  more  water  than  cold  ones,  and  when  a  warm, 
moisture-ladened  current  of  air  encounters  a  colder  one 
the  cold  area  chills  the  warmer  so  that  the  moisture  is 
thrown  out  as  rain  or  snow.  Bain  is  precipitation  in 
warm  or  moderate  weather.  Snow  is  precipitation  from 
clouds  at  a  temperature  below  freezing.  Water  does 
not  form,  but  the  change  is  from  the  gaseous  state  direct 
to  the  solid  or  crystalline  state.  Because  of  the  loose- 
ness of  the  crystalline  structure  it  takes  a  great  many 
inches  of  snow  to  form  one  inch  of  water  on  melting. 
Hail  is  first  precipitated  as  water  and  forms  in  drops, 
which  meet  colder  air  strata,  where  they  are  frozen  to 
the  solid  state.  Dew  is  precipitation  of  moisture  of  the 
air  in  the  lower  strata,  due  to  the  lowering  of  the  tern- 


70  CHEMISTRY  OF  FAMILIAR  THINGS 

perature  at  night.  It  condenses  on  grass,  leaves,  and 
other  objects,  because  of  the  greater  prevalence  of 
moisture  close  to  the  ground  than  elsewhere. 

The  air  may  contain  as  much  moisture  that  is  in- 
visible, showing  a  blue  sky,  at  one  time  as  it  does  at 
another  when  there  are  clouds.  In  the  first  case,  how- 
ever, the  air  must  be  warmer  than  in  the  second.  Clouds 
form  in  a  clear  sky.  They  don 't  have  to  come  from  some 
other  locality,  and  clouds  may  disappear  into  clear  air 
or  blue  sky.  When  the  air  reaches  the  dew  or  precipita- 
tion point,  clouds  form,  the  water  passing  from  the 
gaseous  into  the  vapor  state,  and  the  opposite  is  true 
when  they  disappear.  White  smoke  from  a  locomotive 
or  power  plant  is  moisture  vapor,  and,  if  the  air  is  not 
very  high  in  humidity,  it  is  quickly  absorbed  into  the 
gaseous  (or  invisible)  state  in  the  air.  Humidity  means 
the  percentage  of  moisture  in  the  air  that  it  is  capable 
of  holding  at  that  temperature.  Humidity  60°  means 
it  has  60  per  cent,  of  the  water  it  can  hold  as  gas  at 
that  temperature. 

The  amount  of  water  that  is  required  to  saturate  a 
cubic  yard  of  air  at  different  temperatures  (Fahrenheit) 
is  given  herewith: 

14° 26.8  grains  68° 206.5  grains 

32° 58.6  grains  86° 362.1  grains 

50° 112.6  grains  212° 1.     Ib.  and  81  grains 

One  cubic  mile  of  air  saturated  with  moisture  at  95° 
F.  would  give  up  140,000  tons  of  water  if  cooled  to 


AIR,  OXIDATION,  AND  VENTILATION  71 

32°  F.  The  moisture  ordinarily  present  in  the  air  is 
shown  by  the  condensation  of  water  on  the  outside  of 
a  pitcher  of  ice-water,  where  it  is  precipitated  by  the 
chilling  of  the  layer  of  air  to  its  dew-point. 

Air  seems  to  be  best  for  us  when  the  moisture 
content  is  moderate.  Outside  air  is  rarely  too  dry,  but 
often  too  humid.  It  seems  to  be  purer  and  more  ex- 
hilarating after  a  storm,  unless  in  summer,  when  the 
heat  may  be  intense  and  thus  unpleasant.  For  instance, 
after  a  fall  of  snow  in  winter  the  air  is  moderately  dry 
and  bracing  in  most  localities.  In  winter  the  heated 
air  of  the  houses  is  too  dry,  especially  in  the  Northwest, 
unless  water  is  specially  evaporated  from  pans  on  the 
radiators,  etc.  This  is  because  the  outside  air,  which 
contains  enough  moisture  for  its  temperature,  if  heated 
and  moisture  is  not  supplied,  is  relatively  so  dry  that 
it  tends  to  parch  the  throat  and  air  passages  of  people. 

Ozone  is  caused  by  various  organic  changes  and 
electrical  action,  and  is  soon  consumed  in  oxidizing 
sulphurous1  acid  from  burning  sulphur  in  coal  and  or- 
ganic matter  in  process  of  decay.  Ammonia  and  other 
nitrogenous  gases  are  in  the  air  in  small  quantities  at 
times,  and  removed  by  the  rain,  which  carries  them  into 
the  soil,  for  which  they  are  beneficial.  Hydrogen  sul- 
phide is  nearly  always  in  the  air  in  small  amount,  es- 
pecially in  houses.  It  comes  largely  from  the  toilets. 
This  gas  causes  the  tarnishing  of  silver  and  the  darken- 


72  CHEMISTRY  OF  FAMILIAR  THINGS 

ing  of  white  paints  made  from  white  lead.  For  out- 
houses and  bath-rooms  white  paint  made  from  zinc 
oxide  is  preferable,  as  it  is  not  affected  by  sulphur 
gases.  Besides  the  gases  in  the  air,  there  are  always 
certain  amounts  of  dust  and  bacteria.  Dust  is  delete- 
rious to  the  lungs,  but  it  is  largely  caught  in  the  nasal 
passages  in  breathing.  The  purer  the  atmosphere  is 
with  regard  to  the  dust  the  safer,  and,  as  a  rule,  the 
outdoor  air  contains  less  dust,  especially  at  night,  than 
indoors.  Dust  in  the  air  is  made  visible  by  a  ray  of  sun- 
light. Air  bacteria  are  practically  harmless,  as  patho- 
genic organisms  cannot  live  very  long  subjected  to  air 
and  light  and  so  are  not  found  normally  in  the  air. 

By  intense  artificial  cold  air  can  be  liquefied.  When 
in  the  liquid  state,  freely  exposed,  it  boils  until  all  is 
vaporized,  the  nitrogen  going  off  first,  until  the  air 
is  rich  in  oxygen  (containing  about  93  per  cent.). 
Liquid  air  boils  at  about  —347°  F.,  while  liquid  carbon 
dioxide  does  not  boil  at  so  low  a  temperature,  but  at 
—  112°  F.  If  liquid  air  is  kept  in  a  vacuum,  double- 
walled,  glass  bottle  (it  must  not  be  corked  or  a  violent 
explosion  will  ensue) ,  it  vaporizes  slowly  but  surely.  A 
little  can  be  kept  for  about  ten  days  in  a  vacuum,  or  so- 
called,  Dewar  flask.  This  liquid  is  so  cold  that  it 
changes  mercury  when  in  contact  with  it  into  a  solid 
so  dense  that  it  can  be  used  as  the  head  of  a  hammer 
with  which  to  drive  nails. 


AIR,  OXIDATION,  AND  VENTILATION  73 

According  to  the  nebular  hypothesis,  what  is  now 
our  planet  was  once  a  mass  of  swirling  hot  gases,  or 
rather  the  earth  and  other  planets  revolving  around  the 
sun  constituted  such  a  nebula.  As  these  gases  cooled, 
some  condensed  to  liquids,  which  took  spherical  forms 
due  to  the  rotary  motion  they  had.  Finally,  these  balls 
of  hot  liquid  cooled,  and  one  of  them,  this  earth,  formed 
a  solid  crust  with  gaseous  covering,  which  is  the  air 
we  have  been  describing.  Most  of  the  substances  that 
went  into  this  liquid  condition  and  afterwards  assumed 
solid  form  combined  with  oxygen  to  form  oxides,  such 
as  iron  oxide  in  iron  ore,  silicon  oxide  or  silica,  alu- 
minum oxide  or  alumina,  and  elements  combining  with 
so  much  oxygen  may  account  for  there  being  much 
less  oxygen  in  the  air  than  nitrogen.  Nitrogen,  being 
very  inert,  did  not  go  into  combination.  Many  of  the 
substances  combined  with  oxygen,  or  in  some  cases 
sulphur  (which  acts  like  oxygen  in  many  ways),  have 
been  freed  from  their  combinations  to  make  them  more 
serviceable,  and  thus  we  have  obtained  the  metals. 
If  left  exposed  to  the  weather,  most  of  these  metals 
corrode,  or  oxidize,  at  least  on  the  exposed  surfaces. 
Sodium,  potassium,  calcium,  and  some  other  metals 
quickly  combine  with  oxygen  in  the  cold,  and  are  thus 
converted  into  oxides.  Other  metals,  such  as  aluminum, 
lead,  zinc,  and  copper,  oxidize  on  the  surface  only  and 
the  body  of  the  metal  is  protected.  Iron  or  steel  does 


74  CHEMISTRY  OF  FAMILIAR  THINGS 

not  corrode  except  at  a  red  heat  or  where  moisture  is 
present.  All  these  metals  combine  easily  with  oxygen 
at  a  high  heat.  The  dross  on  lead  when  it  is  melted  is 
oxide,  and  copper  changes  on  oxidation  to  a  black 
powdery  substance.  Most  metals  will  burn  brilliantly 
in  oxygen  if  a  little  heat  is  applied  to  start  reaction. 

Besides  the  oxidation  of  metals,  we  have  that  of 
organic  matter.  This  form  of  oxidation  is  called  com- 
bustion, and  is  treated  in  Chapter  V. 

The  purification  of  the  air  in  buildings  is  one  of 
great  importance,  and  the  subject  is  called  ventila- 
tion. In  summer  this  is  not  a  problem  to  be  considered, 
but  in  winter  it  is  a  live  subject.  Where  open  fireplaces 
are  the  means  of  heating  houses,  they  take  care  of 
the  ventilation  automatically  by  creating  such  strong 
draughts  that  the  fresh  air  from  outside  obtains  an 
entrance.  In  cities,  however,  heating  is  not  done  to  any 
extent  by  open  fireplaces.  Where  the  hot-air  furnace 
is  used  ventilation  is  effected,  but  it  is  very  difficult  to 
supply  the  water  this  warmed  air  requires  at  the  higher 
temperatures.  If  the  outside  air  is  at  32°  F.,  it  has 
only  some  percentage  (according  to  its  humidity,  say  60 
per  cent.)  of  the  possible  water  content  at  this  tempera- 
ture, or  58.6  grains  (see  p.  70),  and  if  heated  to  68°  F. 
it  should  have  the  same  percentage  of  the  total  amount 
of  moisture  possible  at  that  temperature,  or  206.5  grains 
per  cubic  yard.  If  this  moisture  is  not  supplied,  it 


AIR,  OXIDATION,  AND  VENTILATION  75 

makes  a  seriously  dry  atmosphere  to  live  in.  One  that 
ought  to  have,  say,  60  per  cent,  of  206,  or  123.6  grains, 
and  only  has  60  per  cent,  of  58.6,  or  35.1  grains,  or  less 
than  one-third,  is  palpably  deficient  in  moisture.  Water 
is  supplied  sometimes  in  hot-air  heating,  but  the  appli- 
cation is  not  usually  effective. 

Most  installations  for  heating  are,  however,  hot 
water  or  steam,  especially  large  installations,  and  all 
the  ventilating  must  be  done  specially.  Inexpensive 
instruments,  called  hygrometers,  to  show  the  relative 
humidity,  are  of  more  importance  than  thermometers 
in  the  home. 

The  necessity  for  ventilating  is  the  only  part  of  this 
subject  that  seems  to  bear  on  chemistry,  and  there  is 
quite  a  little  difference  of  opinion  among  writers.  The 
art  of  ventilating  is  an  engineering  matter.  Some 
writers  have  held  that  the  air  becomes  impure  because 
of  the  carbon  dioxide  with  which  it  becomes  charged. 
Others  have  more  recently  held  that  it  is  not  so  much 
the  carbon  dioxide  in  the  air,  but  the  fact  that  the  air 
becomes  heated  by  the  presence  of  people  in  a  limited  or 
confined  space,  and  it  is  therefore  less  bracing,  and 
shorter  and  less  beneficial  breaths  are  taken,  due  to  the 
lack  of  exhilaration.  The  third  view  of  the  subject  is 
that  noxious  gases  called  anthrotoxins  are  given  off, 
which  have  really  poisonous  effects  upon  people  breath- 
ing them  in  appreciable  quantity. 


76  CHEMISTRY  OF  FAMILIAR  THINGS 

It  has  been  carefully  figured  out  just  how  much  air 
a  person  needs  by  first  deciding  what  the  limit  of  car- 
bon dioxide  in  the  air  may  be  and  then  showing  how 
much  space  per  person  there  must  be  to  produce  this 
quantity.  The  estimation  of  carbon  dioxide  in  more 
or  less  contaminated  air  is  certainly  a  valuable  indicator 
of  contamination.  By  experience  people  have  been 
able  to  say  when  the  air  was  fresh  or  ventilation  was 
needed,  and  a  limit  of  six  parts  of  carbon  dioxide  per 
10,000  of  air  in  excess  of  what  the  outside  air  contained, 
has  been  given  as  all  that  was  permissible.  It  can  be 
shown  about  how  much  air  a  person  must  have  per  hour 
to  produce  various  degrees  of  contamination  in  a  room. 

Air  supplied  per  Excess  of  COa  due  to 

adult  per  hour  in  respiration  per  10,000 

cubic  feet  by  volume 

1000 6 

1200 5 

1500 4 

2000 3 

3000 2 

There  are  about  four  parts  of  carbon  dioxide  per 
10,000  in  the  air  of  cities,  and,  therefore,  one  adult 
would  double  this  amount  in  1500  cubic  feet  of  confined 
air  in  an  hour.  A  room  12  x  12  by  10  feet  high  would 
contain  nearly  1500  cubic  feet  of  air.  Of  course,  win- 
dows and  doors  are  never  air-tight,  but  there  are  de- 
vices called  metal  weather  stripping  on  the  market  that 
make  them  nearly  so,  and  where  these  are  used  there 


AIR,  OXIDATION,  AND  VENTILATION  TV 

should  be  windows  always  open  on  the  side  of  the  house 
away  from  the  wind.  This  creates  a  current  out  rather 
than  in,  and  the  house  should  be  supplemented  with 
minor  ventilating  openings  on  the  side  toward  the  wind. 

The  second  hypothesis,  in  which  the  deleterious 
effect  is  supposed  to  be  due  to  body  heat,  is  hardly  ten- 
able at  all  times,  as  it  seems  unreasonable  to  the  writer, 
who  has  often  experienced  the  sensation  of  exhaustion 
in  a  crowded  room  and  does  not  believe  it  was  due  to 
heat  alone. 

The  third  proposition  is  that  irritating  or  depress- 
ing gases  are  given  off  from  the  lungs.  What  these 
may  be  would  be  hard  to  show,  as  they  must  be  very 
small  in  amount.  There  is  a  great  difference  in  the 
effect  on  the  system  between  exhilarating  air  and  op- 
pressive air,  even  if  they  should  be  chemically  about  the 
same.  The  safest  way  is  to  ventilate  frequently  to 
attain  an  apparent  freshness  in  the  air,  and  to  minimize 
the  effect  of  toxins,  which  probably  do  exist.  Some 
facts,  without  figures,  with  regard  to  ventilation  may  be 
given.  The  oxygen  necessary  for  life  is  greatest  in 
pure  dry  air  in  low  altitudes.  This  ideal  location  is 
hard  to  find,  as  the  air  is  drier  away  from  the  sea- 
coast.  Moisture  must  be  given  off  in  the  air  from  the 
lungs,  due  to  the  chemical  processes  at  work,  and  there- 
fore the  air  we  breathe  should  not  be  saturated  with 
moisture  on  entering  the  lungs.  Humid  days  in  sum- 


78  CHEMISTRY  OF  FAMILIAR  THINGS 

mer  are  oppressive  because  the  moisture  normally 
taken  up  cannot  be  properly  expelled  from  the  lungs. 
In  rooms  that  are  not  well  ventilated  the  exhaled  mois- 
ture accumulates,  and  this  is  one  of  the  reasons  why 
such  air  becomes  oppressive.  It  would  also  seem  as  if 
air  nearly  saturated  with  humidity  might  hold  active 
deleterious  bacteria  longer  than  dry  air,  as  desiccation 
kills  bacteria.  Certainly  damp,  muggy  weather  causes 
the  spread  of  disease. 

The  amount  of  relative  humidity  of  the  air  may  be 
greater  when  cool  than  heated.  In  the  first  case  it 
might  be  about  80  per  cent.,  but  if  the  air  was  very 
warm  it  should  not  be  much  over  50  per  cent,  humid. 
People  go  to  high  altitudes  for  the  cure  of  lung  diseases, 
probably  as  the  lungs  are  expanded  more  by  the  rarefied 
air,  but  difficulty  comes  sometimes  from  the  heart  being 
unable  to  pump  enough  blood  for  more  rapid  breath- 
ing. Cool  air  is  somewhat  more  satisfying  than  warm 
or  temperate  air,  as  it  is  denser  and  contains  more 
oxygen.  Getting  air  richer  in  oxygen  may  be  and  prob- 
ably is  one  of  the  benefits  of  outdoor  sleeping. 

Bath-room  hoppers  should  be  ventilated  by  posi- 
tive suction.  A  little  examination  will  show  that  very 
few  are  ventilated  in  any  way,  as  the  "stack"  running 
to  the  roof  does  not  ventilate  the  hoppers  of  "body 
gases"  due  to  the  water  trap  between  the  two.  A  real 
ventilating  hopper  can  be  obtained  and  they  are,  I 


AIR,  OXIDATION,  AND  VENTILATION  79 

understand,  installed  in  a  few  office  buildings  in  Phila- 
delphia. 

When  people  learn  to  know  the  air  as  well  as  they  do 
food  or  water,  they  may  choose  their  places  for  vaca- 
tion sojourning  because  of  the  known  properties  of  the 
air.  Places  will  have  to  be  advertised  more  specifically 
as  to  the  bracing  qualities  of  the  air.  They  will  have  to 
tell  what  is  the  average  content  of  oxygen  per  cubic 
metre  at,  say,  70°  F. ;  the  average  relative  humidity, 
the  average  bacterial  content,  the  percentages  of  car- 
bon dioxide,  nitrous  and  nitric  oxide,  ammonia,  and 
ozone  in  the  air,  and,  in  short,  deal  in  facts  and  not  in 
fancies. 

Ozone  is  produced  by  the  rapid  evaporation  of  water 
in  the  direct  sunlight.  A  few  weeks  prior  to  this  time 
of  writing  (March,  1914)  the  writer  had  an  interesting 
experience.  The  snow  covered  the  ground  fairly  com- 
pletely, although  it  had  been  melting  rapidly  for  several 
days.  I  noticed,  one  evening,  a  strong  odor  of  ozone  in 
the  house  and  seemed  to  trace  it  to  an  open  window  in 
which  the  air  was  blowing.  I  felt  I  could  not  mistake 
the  odor  of  ozone,  as  I  have  had  an  ozonizer  for  water 
purification  in  the  laboratory  for  several  years  and 
smell  ozone  from  it  daily.  The  next  morning  I  took  the 
train  to  about  one  hundred  miles  west  of  Philadelphia 
and  noticed  the  same  odor  on  the  way,  due  undoubtedly 
to  the  bright  sun  shining  on  the  snow  and  quickly 


80 


CHEMISTRY  OF  FAMILIAR  THINGS 


evaporating  the  water.  One  evening  in  April,  when  I 
again  noticed  the  very  pleasant  indication  of  ozone  in 
the  air,  I  tested  for  its  presence  with  filter  paper  satu- 
rated with  solutions  of  potassium  iodide  and  starch 
water.  Ozone  acts  upon  the  potassium  iodide  with  liber- 
ation of  iodine,  which  has  the  property  of  turning 
starch  to  a  violet  color.  A  violet  colorization  was 


Fio.  3.— Air  ozonator.  High-voltage  discharge  tubes  at  top  of  stand.  Blower  at  bottom. 

noticed  on  several  pieces  of  this  paper  the  next  morning. 
This  effect  was  very  noticeable  by  me  a  few  evenings 
in  March  and  April,  but  not  later  in  the  season. 

Ozone  is  artificially  produced  from  air  by  means  of 
generators  in  which  high-voltage  currents  discharge 
through  glass  plates  or  cylinders.  In  the  dark  one  can 
see  a  blue-violet  glow  or  so-called  silent  discharge  in  the 


AIR,  OXIDATION,  AND  VENTILATION  81 

ozonizer.  The  writer  lias  found  such  ozonized  air  valu- 
able in  neutralizing  escaping  hydrogen  sulphide  gas  in 
chemical  manufacturing  operations.  The  ozone  gener- 
ated should  be  strong  enough  to  neutralize  this  gas  but 
not  enough  to  be  very  noticeable  in  itself.  Ozonized  air 
seems  well  adapted  to  use  in  churches  and  halls,  al- 
though fresh,  cool  air  in  quantity  should  be  preferable. 
Ozone  certainly  purifies  the  air  from  traces  of  organic 
matter,  and  it  is  claimed  by  some  authorities,  but  denied 
by  others,  that  bacteria  in  the  air  are  killed  by  it.  It 
is  generally  desirable  to  cool  air  artificially  in  crowded 
halls,  even  in  winter  time,  as  every  person  is  at  a  tem- 
perature of  98.8°  F.  and  when  packed  closely  they  will 
tend  strongly  towards  raising  the  temperature. 


CHAPTER  VII 

WATER 

WATER  is  the  most  universally  distributed  and  im- 
portant substance  we  have.  It  permeates  the  universe, 
saturating  the  rocks  and  soil  except  at  the  very  surface 
where  the  sun  may  partially  dry  things.  Water  may  wet 
substances  like  sand,  but  it  will  pass  off  again  if  they 
are  put  in  a  warm  dry  place,  or  it  may  be  chemically 
combined  as  water  of  constitution  or  crystallization. 
Gypsum  contains  water  of  this  kind,  and  so  it  must 
be  heated  to  a  temperature  above  212°  F.  to  give 
up  this  water.  It  is  then  plaster  of  Paris,  and  it  will 
set  again  in  solid  form  when  water  is  mixed  with  it. 
Portland  cement  also  takes  up  water  to  form  a  hy- 
drated  composition,  which  operation  constitutes  a 
chemical  change.  Water  is  the  chief  substance  in  the 
vital  fluids  of  animal  and  plant  life,  and  our  bodies  are 
more  than  eighty  per  cent,  water. 

Water  has  such  a  simple  chemical  formula  that 
people  remember  it  when  they  cannot  recall  other 
chemical  formulae.  It  is  formed  by  the  union  of  two 
volumes  of  hydrogen  and  one  of  oxygen,  making  two 
volumes  of  water  vapor.1  Water  is  composed  of  eight 
parts,  by  weight,  of  oxygen  to  one  part  of  hydrogen  and 


82 


WATER  83 

is  represented  by  the  formula  H20.  Both  of  these 
elements  are  gases  when  uncombined.  So  it  is  easy  to 
realize  that  their  union  produces  a  chemical  change.  If 
a  grain  of  metallic  sodium  is  dropped  into  a  bowl  of 
water,  the  elements  forming  the  water  by  chemical 
union  are  separated.  The  oxygen  goes  to  the  sodium, 
forming  sodium  oxide,  which  unites  with  more  water, 
forming  sodium  hydroxide  or  caustic  soda  (a  base). 
Hydrogen  gas  is  given  off,  accompanied  by  so  much 
liberated  heat  that  it  frequently  burns  and  forms  water 
again  with  the  oxygen  of  the  air.  If  a  cold  metal  plate 
is  held  above  the  flame  of  the  burning  hydrogen,  the 
surface  will  become  moistened  from  the  water  formed. 

Another  interesting  experiment  consists  in  filling 
two  volumes  of  hydrogen  and  one  volume  of  oxygen 
into  the  same  rubber  bag,  and  then  blowing  soap  bubbles 
with  this  gas,  put  under  slight  compression.  These 
bubbles  are  lighter  than  air,  due  to  the  influence  of  hy- 
drogen, the  lightest  known  gas,  and  rise  in  the  air.  Just 
before  they  pass  out  of  reach  of  the  experimenter,  they 
are  lit  by  a  taper  and  explode  with  considerable  noise 
caused  by  the  energetic  union  of  the  two  gases  with  each 
other  to  form  water. 

Water  is  used  as  a  standard  for  determining  the 
relative  weights  of  unit  volumes  of  substances  which  we 
call  specific  gravity  or  density.  Water,  then,  has  a 
density  of  unity  or  1.00.  Alcohol  is  lighter  and  has  a 


84  CHEMISTRY  OF  FAMILIAR  THINGS 

density  of  0.785  when  pure,  and  sand,  which  is  heavier, 
has  a  specific  gravity  of  about  2.5,  iron  7.9,  and  mercury 
13.6.  All  substances  have  a  certain  capacity  for  hold- 
ing heat.  It  is  a  circumstance  that  water  has  the 
greatest  such  capacity,  or,  as  we  have  seen  before, 
specific  heat.  This  property  is  made  use  of  in  water 
heating.  If  water  did  not  have  a  large  heat  capacity 
it  would  not  serve  as  an  efficient  means  of  distribution 
or  storing  of  heat.  In  some  fireless  cookers  a  dish  to  be 
cooked  is  heated  to  the  proper  temperature  and  also  a 
larger  volume  of  water  is  heated  to  boiling  and  all  is 
put  in  a  well-insulated  container.  The  water  holds  so 
much  heat  that  it  can  give  off  enough  to  complete  the 
cooking  of  a  vegetable  or  cereal  that  has  been  heated 
only  a  very  short  time  over  direct  fire. 

There  are  a  few  other  important  points  about  water, 
ice  (solidified  water),  and  steam  (gasified  water). 
Water  solidlles  to  form  ice  at  32°  F.  If  heat  is  with- 
drawn from  water  the  temperature  falls  until  at  32°  F., 
and  although  the  surroundings  are  below  32°  F.,  the 
temperature  remains  constant  until  all  the  water  is  fro- 
zen. Of  course,  when  once  frozen,  the  ice  will  become 
colder  in  accordance  with  the  temperature  of  the  air. 
One  peculiarity  of  water  on  freezing  is  that  it  expands  in 
volume  and  its  density  is  diminished  by  about  6  per  cent. 
The  importance  of  this  to  the  householder  and  others 
is  that  water  must  not  be  left  in  pipes  exposed  to  freez- 


WATER  85 

ing  conditions,  for  the  force  of  the  expansion  is  great 
enough  to  burst  iron  pipes.  Large  pipes  are  not  so  apt 
to  burst  as  small  ones,  as  ice  is  not  a  good  conductor  of 
heat,  and,  after  a  coating  forms  on  the  inside  of  the 
pipes,  the  rest  of  the  water  can  flow  back  upon  the  city 
pressure. 

Water  boils  forming  steam  at  212°  F.  at  the  normal 
pressure  of  the  atmosphere,  or  29.9  inches  of  mercury 
(760  millimetres).  When  heat  is  applied  the  tempera- 
ture rises  until  212°  F.  is  reached  and  then  remains 
constant  until  the  water  is  all  converted  into  steam. 
This  means  that  when  water  is  boiling  slowly  it  is  just 
as  hot  as  when  boiling  rapidly.  If  this  fact  were  re- 
alized in  the  kitchen  much  fuel  would  be  saved.  The 
most  suitable  conditions  for  removing  water  or  drying 
things  are  to  have  heat  and  means  of  conducting  off 
the  steam  or  vapor.  Only  moderate  heat  or  warmth  is 
requisite  for  water  loosely  held  and  with  plenty  of 
surface  exposed ;  the  other  requisite  is  a  current  of  air 
or  other  means,  such  as  vacuum,  to  remove  the  water 
vapor.  If  water  is  the  chief  component,  as  in  a  solution, 
higher  heat  is  desirable  and  ventilation  is  secondary  in 
importance.  The  condition  of  the  atmosphere  often 
plays  an  important  part  in  drying,  for  with  a  high 
humidity  (the  air  charged  with  moisture)  drying  is  less 
readily  effected  than  with  a  low  humidity. 

Absolutely  pure  water  is  not  a  conductor  of  elec- 


86  CHEMISTRY  OF  FAMILIAR  THINGS 

tricity,  but  the  slighest  impurity  gives  it  some  conduc- 
tivity, so  that  all  natural  waters  are  moderately  good 
electrical  conductors.  Dry  wood  is  an  insulator.  A  tree 
attracts  lightning  because  of  the  water  in  the  sap. 
Water  dissolves  many  substances,  such  as  many  salts 
(besides  common  salt),  sugars,  gums,  most  acid  and  all 
alkaline  substances.  It  mixes  with  or  dissolves  alcohol 
and  glycerin;  these  when  taken  alone  are  solvents  for 
some  things  that  water  cannot  dissolve,  but  other  sol- 
vents, such  as  gasolene,  benzol,  chloroform,  carbon 
tetrachloride,  carbon  disulphide,  and  ether,  are  not  dis- 
solved by  water  to  any  very  appreciable  extent  and  are 
called  immiscible  solvents ;  in  most  cases  they  dissolve 
substances  not  affected  by  water. 

What  has  been  said  above  relates  to  pure  water. 
Natural  waters  are  not  quite  pure,  as  they  have  some 
substances  in  solution.  In  most  cases  the  matter  in 
solution  is  not  great  in  quantity  but  it  has  a  consider- 
able effect  in  sanitary  engineering.  The  impurities  are 
generally  measured  in  parts  per  hundred  thousand  or 
million,  or  in  grains  per  gallon.  A  good  water  will  have 
less  than  five  hundred  parts  per  million,  or  twenty-nine 
grains  per  U.  S.  gallon  of  solid  matter.  The  author  has 
analyzed  a  natural  water  with  solids  as  low  as  seven- 
tenths  of  a  grain  per  U.  S.  gallon,  but  natural  waters 
with  as  little  as  a  grain  per  gallon  are  rare. 

The  solids  consist  of  inorganic  matter,  such  as  sul- 


WATER  87 

pliates,  carbonates,  and  chlorides  of  calcium,  magne- 
sium, sodium,  and  potassium,  and  generally  a  smaller 
amount  of  organic  matter.  The  organic  matter  may 
come  from  leaf  mould  or  other  vegetable  matter,  and  in 
cases  of  contamination  from  animal  matter  (sewage 
contamination) .  Of  course,  the  presence  of  the  latter  in 
water  is  sufficient  to  condemn  it  for  potable  use.  Arte- 
sian well  waters  are  usually  free  from  organic  contami- 
nation, and  so  are  deep  spring  waters,  but  surface 
waters  are  likely  to  be  more  or  less  contaminated  and 
they  are  not  much  used  for  municipal  supply  without 
some  form  of  purification. 

Those  who  have  not  studied  chemistry  would  have 
difficulty  in  understanding  a  chemist's  report  on  a 
water,  in  spite  of  his  efforts  to  be  non-technical.  Many 
people,  however,  are  from  time  to  time  interested  in 
ascertaining  the  purity  of  a  spring  or  well  water.  There 
is  a  prevailing  impression  that  a  sparkling  spring  water 
must  be  absolutely  pure  and  safe.  This  is  no  criterion, 
as  a  sparkling  water  may  be  dangerous  and  a  turbid 
water  may  be  perfectly  safe.  A  water  may  be  undesir- 
able because  of  a  disagreeable  odor,  turbid  condition, 
a  taste  of  iron,  excessive  temporary  hardness,  excessive 
permanent  hardness,  discoloration,  excessive  saline 
matter,  etc.  A  water  may  be  unsafe  because  of  patho- 
genic bacteria.  Of  course,  a  very  hard  water  may  be 
unsafe  for  people  subject  to  rheumatism,  etc.,  but  there 


88  CHEMISTRY  OF  FAMILIAR  THINGS 

is  just  one  thing  that  ordinarily  makes  a  water  unsafe, 
and  that  is  the  presence  of  disease-producing  bacteria, 
and  probably  the  one  most  likely  to  cause  trouble  in 
water  is  Bacillus  (B.)  typhosus. 

Most  waters  that  are  condemned  by  chemists  are  not 
criticised  because  B.  typhosus  is  found,  but  because  of 
the  finding  of  elements  that  indicate  sewage  contamina- 
tion. These  substances  themselves  are  practically 
harmless,  but  if  water  shows  appreciable  quantities  of 
sewage  admixture  it  is  always  unsafe  even  if  B.  typho- 
sus  is  not  found  in  a  sample.  For  instance :  albuminoid 
ammonia  indicates  nitrogenous  matter;  free  ammonia 
indicates  partially  oxidized  nitrogenous  matter ;  nitrites 
indicate  a  further  state  of  change,  and  nitrates  indicate 
a  final  state  of  change  from  the  original  protein  or 
nitrogenous  matter  coming  from  animal  decomposition. 

Quantities  of  the  first  three  substances  indicate  more 
or  less  recent  contamination,  while  the  last-mentioned 
may  mean  that  the  organic  matter  is  so  fully  oxidized 
that  bacteria  which  accompanied  the  original  nitrog- 
enous matter  must  have  been  killed  by  the  oxidizing 
influences,  as  pathogenic  organisms  do  not  live  long 
where  the  oxidizing  action  of  the  air,  especially  in  the 
sunlight,  has  full  play.  Besides  these  nitrogenous 
substances,  chlorides  and  phosphates,  especially  the 
latter,  indicate  contamination  from  sewage. 

In  addition  to  these  chemical  tests  there  are  some 


Photo  by  the  Author. 

Electric  water  ozonizer,  showing  glass  plates  with  tinfoil  surfaces. 


t 


Photo  by  the  Author.  » 

Petri  dishes,  showing  method  of  counting  bacteria  in  water.    Sample  on  left  contaminated; 

on  right,  sterile. 


WATER  89 

bacteriological  ones  that  may  be  briefly  considered. 
The  total  bacteria  in  a  unit  volume  of  water  (1  cubic 
centimetre,  or  c.c.)  are  counted  under  standard  condi- 
tions :  sometimes  the  test  is  made  at  ordinary  tempera- 
tures, about  70°  F.  (20°  C.),  and  sometimes  the  test  is 
made  at  blood  heat,  98°  F.  (38°  C.).  A  bacteriolog- 
ical test  that  is  often  made  is  a  specific  test  for  the 
colon  bacillus.  While  B.  coli  are  not  very  dangerous 
themselves,  they  are  nevertheless  always  in  the  human 
intestinal  tract,  from  which  they  derive  the  name  colon, 
and  where  they  are  found  B.  typhosus  may  also  be 
found,  and  one  would  be  taking  undue  chance  in  using 
such  a  water. 

The  bacteria  are  counted  in  an  ingenious  way.  They 
are  too  small  to  be  counted  singly  with  proper  accuracy 
in  any  unit  volume,  even  with  a  high-power  microscope, 
so  a  solution  is  made  with  nutrient  material,  such  as 
beef  broth  and  peptone,  and  enough  pure  gelatin  so 
that  it  becomes  a  solid  jelly  when  cold.  This  nutrieilt 
gelatin  is  sterilized  and  kept  in  tubes  plugged  with 
sterile  cotton.  When  a  little  water  to  be  tested  is  mixed 
with  this  nutrient  solution  after  warming  slightly  and 
spreading  out  in  a  flat  glass  sterilized  dish  (called  a 
Petri  dish)  and  kept  covered  at  the  right  temperature, 
each  bacterium  grows  by  a  process  of  subdivision  until 
there  is  a  big  family  or  colony  where  each  one  was  in  the 
medium  before  it  was  chilled.  When  the  jelly  is  stiff 


90  CHEMISTRY  OF  FAMILIAR  THINGS 

they  grow  en  masse,  and  these  colonies  can  be  counted 
in  a  couple  of  days  by  the  unaided  eye.  When  the  test 
is  made  at  98°  F.  a  gelatinous  substance  called  agar  or 
agar-agar  is  used  instead  of  gelatin,  as  it  will  keep  the 
broth  stiff  even  at  this  rather  elevated  temperature. 

If  a  water  is  found  to  have  B.  coli  present,  it  should 
be  condemned.  Very  many  of  any  kind  of  bacteria,  say, 
over  200  to  500,  depending  upon  the  source,  and  when 
the  test  is  made  at  blood  heat,  any  which  produce  acid, 
throw  suspicion  upon  the  water.  These  rather  technical 
points  are  gone  into  briefly  because  people  must  be  in- 
terested in  the  water  they  drink,  and  circulars  and 
folders  of  water  companies  and  summer  hotels  gen- 
erally contain  analyses  of  water  from  their  particular 
springs,  etc. 

Some  waters  show  a  little  radio-activity,  but  the  in- 
fluence of  such  waters  is  not  well  known  at  present,  and 
we  do  know  that  an  abundance  of  pure  ordinary  water 
is  very  beneficial,  and  radio-active  waters  might  as  well 
be  left  alone  until  a  definite  beneficial  effect  is  es- 
tablished. 

Many  waters  are  celebrated  as  curative  waters  be- 
cause they  are  carbonated,  chalybeate,  saline  or  alka- 
line, magnesian,  etc.,  but  the  probability  is  that  in  most 
cases  where  cures  are  effected  it  is  because  of  the  quan- 
tity of  water  drunk,  the  times  when  taken,  the  air,  exer- 
cise, and  general  stimulating  effect  of  the  active  out- 
door life  or  prescribed  routine  at  these  famous  springs. 


WATER  91 

But  resorts  at  the  seashore  where  the  water  is  known 
to  be  pure  and  where  ozone  is  in  abundance  in  the  air, 
or  the  mountains  for  those  who  prefer  them,  are  ex- 
tremely effective  places  for  those  who  cannot  cross  the 
ocean  to  go  to  some  world-famous  mineral-spring  re- 
sort. The  effect  of  drinking  an  abundance  of  water  is 
essentially  a  cleansing  one.  Before  eating,  it  clears  out 
and  washes  the  stomach.  At  any  time  taken,  it  dilutes 
the  blood  so  that  it  can  carry  off  all  the  waste  nitrog- 
enous matter,  such  as  uric  acid,  which  is  not  very 
soluble,  and  so,  logically,  abundance  of  water  is  needed 
fully  to  remove  it  from  the  system. 

We  have  referred  to  temporarily  hard  water  and 
permanently  hard  water.  Temporary  hardness  2  is  due 
to  calcium  bicarbonate  in  solution,  and  when  the  water 
is  heated  it  is  deposited  as  a  sediment  of  calcium  car- 
bonate. Generally  there  are  both  kinds  of  hardness, 
and  boiling  alone  does  not  throw  out  the  substances 
causing  the  permanent  hardness.  If,  in  addition  to  boil- 
ing the  water,  a  little  sodium  carbonate  or  washing  soda 
be  added  to  the  water  while  boiling,  the  water  is  ren- 
dered perfectly  soft.  This  permanent  hardness  3  is  due 
to  calcium  sulphate  (sulphate  of  lime),  magnesium  sul- 
phate, calcium  or  magnesium  chlorides,  any  or  all  of 
them. 

2 Reaction  of  softening  temporarily  hard  water:  CaH2(CO3)2  + 
heat  =  CaCOa  +  H2O  +  C02. 

8  Reaction  for  removal  of  calcium  sulphate  by  means  of  soda :  CaS04 
+  Na2CO3  =  Na2S04  +  CaC03. 


92  CHEMISTRY  OF  FAMILIAR  THINGS 

It  does  not  matter  whether  it  is  in  the  domestic  boiler 
or  one  in  the  factory,  the  happenings  are  about  the 
same.  The  only  difference  is  that  better  precautions 
can  be  taken  to  remedy  matters  on  a  large  scale,  as  in 
factory  operations.  In  the  home  calcium  carbonate  is 
freed  in  the  water-back  of  the  stove  or  gas  heater  and 
deposited  in  the  boiler.  The  permanent  hardness  re- 
mains. In  the  factory  sodium  carbonate  may  be  added 
(called  soda  ash,  technically)  to  remove  the  permanent 
hardness,  and,  instead  of  having  a  deposit  in  the  boiler 
where  steam  is  generated,  the  deposit  forms  in  a  pre- 
heater,  where  it  is  filtered  off.  In  the  home  a  good  deal 
of  the  deposit  that  forms  in  the  boiler  could  be  drawn 
off  from  a  spigot  at  the  bottom  of  the  boiler,  from  time 
to  time,  but  how  many  people  know  what  the  spigot  is 
there  for? 

When  it  comes  to  washing,  water  can  easily  be  soft- 
ened by  the  use  of  washing  soda,  or,  better,  soda  ash,  if 
it  can  be  had,  as  it  is  an  easily  handled  powder  and  is 
cheaper  for  what  it  does  than  washing  soda.  This 
effect,  it  seems  to  the  author,  was  better  understood  a 
generation  ago  than  now.  At  present  many  people  will 
use  a  soap  powder  in  preference  to  washing  soda 
or  borax.4 

4  Softening  with  borax  is  very  much  like  that  with  washing  soda : 
Borax  Calcium  Sodium  Calcium 

sulphate  sulphate  borate 

Na2B4O7.+      CaSO*    —      Na2SO4    +     CaB4O7 


PLATE   VI. 


Courtesy  of  Williams,  Brown  &  Earle. 

Beautiful   effect   in   Luray   Cave   due   to   calcium   carbonate   separated   from   bicarbonate 

solution. 


WATER  93 

A  soap  powder  is  a  mixture  of  soap  and  soda  ash, 
and  a  very  poor  soap  is  apt  to  be  used.  It  would  seem 
the  more  rational  procedure  to  soften  a  tub  of  water 
first  with  a  few  spoonfuls  of  washing  soda,  so  that  it 
readily  makes  good  suds,  and  then  to  use  the  preferred 
kind  of  soap. 

Water  is  purified  for  municipalities  largely  by  sand 
filtration.  The  sand  is  graded  with  coarse  at  the  bottom 
and  running  to  fine  at  the  top.  The  water  is  forced 
slowly  downward  from  the  top,  and  the  fine  sand  catches 
not  only  suspended  matter  but  bacteria  as  well,  by  some 
process  of  attraction  possessed  by  the  bacteria  for  sand. 
It  may  be  such  an  attraction  as  that  of  rocks  and  oyster 
spawn,  due  to  the  glutinous  character  of  the  latter.  At 
all  events  it  happens,  and  if  properly  managed  and  not 
overworked  such  filters  produce  a  safe  water.  Fortu- 
nately, the  dangerous  bacteria  are  killed  easier  than  the 
others,  so  it  is  not  necessary  to  remove  all  to  make  the 
water  good.  If  a  natural  water  contained  from  1000  to 
10,000  bacteria  per  c.c.,  it  might  be  said  that  a  filter 
would  be  satisfactory  if  it  reduced  the  number  to  25 
or  50  per  c.c. 

In  many  places  the  normal  supply  is  subject  to  some 
doubt,  and  so  it  is  frequently  necessary  to  purify  the 
water  in  the  home.  One  can  boil  the  water  and  cool  it, 
which  renders  it  pure,  and  if  stood  to  cool  in  stone- 
ware jars  it  will  in  a  day's  time,  or  thereabout,  take  up 


94 


CHEMISTRY  OF  FAMILIAR  THINGS 


fresh  oxygen  to  replace  what  was  lost  in  boiling,  and  be 
palatable.  It  can  be  distilled  and  aerated  by  cooling 
under  proper  conditions.  The  most  practical  ways  are 


Fio.  4. — Ultra-violet  water  sterilizer. 


ozonizing  and  treatment  with  ultra-violet  light.  An 
ozonizer  is  shown  on  Plate  V,  and  a  line  drawing  of  the 
latter  in  Fig.  3.  The  active  effect  comes  from  a  mercury 
vapor  lamp  to  which  the  current  runs  from  binding 
posts  C  and  D. 


WATER  95 

Domestic  sand  and  charcoal  niters  are  not  very  reli- 
able, as  they  cannot  be  kept  in  perfect  order.  There 
ig  another  way,  but  too  slow  to  be  practicable,  and  it 
might  not  work  in  the  hands  of  people  who  could  not 
check  up  the  purity  of  the  water  by  tests.  The  Bible 
speaks  of  putting  water  in  stone  jars,  "after  the  manner 
of  purifying  of  the  Jews. ' '  The  author  years  ago  while 
yachting  had  experience  in  purifying  on  a  small  scale 
the  worst  kind  of  river  water  (the  Delaware  water  below 
Philadelphia)  by  simply  putting  it  into  a  wooden  cask 
and  leaving  it  in  the  sun.  In  two  weeks'  time  it  was 
pure  and  sweet,  although  it  had  gone  through  a  foul 
stage  in  the  meantime.  The  bacterial  life  had  gone  on 
until  the  organic  food  had  become  exhausted,  and  then, 
of  course,  the  bacteria  died  as  people  would  if  they  had 
no  food  for  a  period.  This  method  might  not  work  in 
winter  or  would  take  much  longer.  It  should  not  be 
tried  unless  the  water  so  treated  were  tested,  or  unless 
the  foul  stage  was  noticed  as  intermediary  and  plenty 
of  time  was  allowed  to  elapse  after  it. 

Fresh  waters  consist  essentially  of  [(a)  rain  water, 
(b)  waters  of  rivers  and  lakes,  (c)  waters  from  springs 
and  shallow  wells,  (d)  artesian-well  waters. 

Eain  water  is  nature's  distilled  water,  and  contains 
only  small  amounts  of  nitrates,  ammonia  salts,  carbon 
dioxide,  etc.,  taken  up  from  the  air.  It  usually  contains 
from  3  to  6  parts  of  solids  per  100,000. 

Surface  waters  vary  greatly.   In  regions  where  the 


96  CHEMISTRY  OF  FAMILIAR  THINGS 

rock  is  silicious  solids  may  be  as  low  as  4  parts  per 
100,000,  while  in  limestone  regions,  especially  where  the 
water  has  taken  up  acid  from  mine  waters,  it  should  not 
contain  more  than  50  parts.  Eiver  waters  become  much 
polluted  with  organic  matter  and  we  have  mentioned  the 
indications  of  such  character.  It  is  highly  desirable 
that  cities  and  towns  should  all  treat  their  sewage,  and 
all  counties  should  insist  upon  proper  cesspools,  such 
as  are  described  on  page  257,  or  better.  Springs  vary 
as  much  as  rivers  in  mineral  contents,  although,  as  a 
rule,  these  are  less.  The  waters  are  free  from  organic 
contamination  only  when  isolated  and  free  from  any 
infiltrations  from  household  sewage  and  barnyards. 
Waters  from  below  the  rock  strata  are  pure,  but  are 
apt  to  run  high  in  mineral  matter.  When  they  run 
above  50  or  60  parts  of  mineral  matter  per  100,000,  they 
are  not  suitable  for  domestic  use  nor  for  boiler  pur- 
poses. They  often  contain  dissolved  iron,  which  is 
removed  as  reddish  flooculent  matter  on  aeration. 

Sea  water  contains  about  3500  parts  of  solids  per 
100,000.  A  typical  analysis  of  sea  water  is  as  follows : 

Sodium  chloride 2706  Potassium  chloride. .  77 

Magnesium  chloride 367  Calcium  carbonate. .   3 

Magnesium  sulphate 230  Magnesium  bromide.  3 

Calcium  sulphate 141 

A  brief  statement  of  the  most  important  classes  of 
mineral  waters  may  be  of  interest,  as  they  often  prove 
of  value  medicinally.  A  brief  resume  is  as  follows : 


WATER  97 

Carbonated  waters  are  saline  and  contain  bicarbon- 
ates  and  free  carbon  dioxide. 

Alkaline  waters  contain  free  sodium  carbonate  and 
bicarbonate. 

Magnesium  waters  have  predominantly  magnesium 
sulphate  and  bicarbonate.  They  are  purgative  in  their 
action. 

Chalybeate  waters  contain  salts  of  iron,  especially 
the  bicarbonate,  which  decomposes  and  precipitates 
ferric  hydroxide  on  standing  or  aeration. 

Calcic  or  hard  waters  are  rich  in  lime  salts.  Most 
waters  are  more  or  less  hard. 

Sulphur  waters  contain  hydrogen  sulphide  in  solu- 
tion and  also  sulphides. 


CHAPTER  VIII 

ALKALIES   AND   SALTS 

IN  THE  present  section  we  will  treat  of  alkalies  and 
their  combinations  with  acids,  called  salts.  The  metals 
producing  these  alkalies — namely,  lithium,  sodium, 
and  potassium — uncombined,  are  not  stable  in  the  air ; 
therefore,  they  are  not  used  by  themselves,  so 
only  a  bare  mention  need  be  made  of  them.  Alkali 
metals  form  the  strongest  bases  because  of  their  af- 
finities for  acids  or  acid  radicles.  Most  of  the  salts, 
however,  are  well  known,  but  the  few  that  are  not 
known  to  the  lay  reader  will  be  worth  giving  the 
attention  here  suggested,  as  the  effort  is  made 
not  to  dwell  on  substances  of  little  interest  more 
than  enough  to  connect  up  the  more  important 
elements. 

Lithium  is  used  only  in  medicine,  as  a  specific  for 
rheumatism,  as  its  salts  are  solvents  for  uric  acid. 

Sodium  in  combination  is  one  of  the  most  commonly 
occurring  elements.  When  the  word  sodium  is  used 
it  may  mean  the  metal  itself  or  it  may  refer,  as  in  this 
particular  case,  to  the  metal  in  combination.  In  nature 
it  is  always  found  in  combination  and  generally  as  chlo- 
98 


ALKALIES  AND  SALTS  99 

ride  or  Common  salt.  The  metal,  sodium,  is  made  at 
Niagara  Falls  by  electrolysis  and  is  used  in  the  manu- 
facture of  some  chemicals.  It  can  be  kept  only  under 
kerosene,  as  water  attacks  it  violently,  and  so  does  air. 
A  small  piece  dropped  into  water  melts  and  assumes  a 
spherical  shape,  rolls  around  on  the  surface  violently, 
giving  off  hydrogen,  which  frequently  burns  because  of 
the  heat  of  reaction  with  the  water.  The  net  result  is 
water  containing  sodium  hydroxide,  which  has  an  alka- 
line reaction.1 

Sodium  Jiydroodde  is  used  largely  for  soap-making 
and  neutralizing  acids,  as  in  refining  vegetable  and 
mineral  oils.  It  is  shipped  in  hermetically  sealed  thin 
sheet-steel  drums,  into  which  it  is  cast  whilst  hot  and 
molten,  and  the  drum  must  be  cut  away  and  the  mass 
broken  up  to  use  it.  It  is  corrosive  to  the  skin,  and  the 
fine  dust  made  when  it  is  broken  up  or  emptied  in  a  dry 
state  from  one  container  to  another  is  very  irritating 
to  the  nostrils  ;  consequently,  workmen  handling  it  must 
wear  gloves  and  aspirators  with  moistened  sponges  to 
intercept  the  particles.  "When  sodium  hydroxide  (lye) 
is  used  in  hot  solution  to  open  drains  or  pipes,  it  is 
effective  by  its  saponifying  action  on  fats.  The  mere 


+       2H2O      —     2NaOH     +  H2 

Sodium  Water  Sodium  Hydrogen 

hydroxide 


100  CHEMISTRY  OF  FAMILIAR  THINGS 

addition  of  this  material  to  water  causes  a  heating 
up  of  the  solution. 

Sodium  hydroxide  or  common  lye  is  made  from  salt 
in  different  ways,  especially  by  electrolysis.2  The  chlo- 
rine that  escapes  may  be  led  into  slaked  lime,  when 
bleaching  powder  is  produced.  This  substance  is  used 
in  the  home  and  factory  for  whitening  wood  pulp, 
cotton,  or  linen.  Bleaching  powder  is  now  put  up  in 
metal  cans  holding  a  pound  each,  with  sifting  tops,  and 
explicit  directions  are  given  for  bleaching  goods,  in- 
cluding the  use  of  washing  soda  with  the  bleach  to  make 
Labarraque's  solution,  or  sodium  hypochlorite.  Straw 
for  hats  and  braids  is  generally  bleached  with  hydro- 
gen dioxide  solutions  at  moderately  elevated  tem- 
peratures. 

Sodium  compounds  are  not  usually  colored  or  in- 
teresting in  any  way  except  that  they  are  very  useful, 
which  makes  it  desirable  to  give  this  space  to  them. 
They  are  invariably  soluble,  except  when  combined  as 
complex  silicates,  such  as  feldspar  or  glass.  The  im- 
portant line  of  compounds  of  sodium  which  are  much 
used  in  manufacturing,  in  the  household,  and  in  medi- 
cine, are  as  follows  : 


2  2NaCl+  (electricity  )+  H2O  =    2NaOH     +       C12     +       H2 
Sodium  chloride  Water     Sodium  hy-     Chlorine    Hydrogen 

(salt)  droxide 


ALKALIES  AND  SALTS   :•'•];  101 

Name  Formula  Use 

Salt NaCl  Condiment     and     to 

make  chemicals. 

Sodium  hydroxide NaOH  To     make     soap     and 

(caustic  soda  or  lye)  chemicals. 

Sodium  carbonate Na2CO3  Cleaning,     soap     pow- 

( soda  ash,  sal  soda,  soda  crystals)  ders,  scouring,  and 

chemical  purposes. 

Acid  sodium  carbonate NaHC03          Baking  powders,  etc. 

(sodium  bicarbonate,  saleratus) 

Sodium  sulphate NajjSO*  .  HaO  Glass  -making    and 

(Glauber's  salt)  wood  pulp. 

Sodium  phosphate   (normal) Na2HPO4         Medicine 

Trisodium  phosphate Na3P04  Water  softening. 

Sodium  dichromate Na2Cr2O7         Tanning. 

Sodium  thiosulphate Na2S203          Tanning    and   photog- 

( sodium  hyposulphite)  raphy. 

Sodium  nitrate NaN03  Agriculture    and 

chemicals. 

Sodium  borate Na2B407          Cleaning    and   use   as 

(borax)  mild  alkali. 

Sodium  silicate Na^SiOs  Soap  filling,  silk  dye- 

ing, etc. 

Sodium  chlorate NaClOa  Pyrotechnics,  e  x  p  1  o  - 

sives    and    textile 
work. 
Sodium  peroxide NagOa  Bleaching. 

Some  people  confuse  the  two  carbonates  of  sodium, 
the  ordinary  carbonate  (Na2C03),  known  among 
chemists  as  sodium  carbonate,  among  manufacturers 
as  soda  ash,  and  in  the  household  as  washing  soda,  with 
the  bicarbonate.  When  fully  crystallized  with  water 
sodium  carbonate  is  much  diluted,  as  it  has  ten  mole- 
cules of  water,  Na2C03 . 10H20.  The  compound  gives 
off  water  easily  on  standing  uncovered,  changing  from 
moist  crystals  to  dry  powder  which  still  has  one  mole- 


102         v  i  ;--  ;  CHEMISTRY  OF  FAMILIAR  THINGS 

cule  of  water.  The  molecular  weight  in  the  first  case 
is  about  106  and  in  the  second  case  186.  Sodium  car- 
bonate is  sold  now  as  monohydrate  with  a  molecular 
weight  of  124.  It  is  easy  to  see  that  dry  soda  is  cheaper 
than  the  crystals  at  anything  like  the  same  price.  So- 
dium bicarbonate  (NaHC03)  has  only  one-half  of  the 
hydrogen  of  carbonic  acid  (H2C03)  neutralized,  and 
has  twice  as  much  C02  gas  that  it  may  give  off  as  the 
normal  sodium  carbonate  based  on  the  sodium  in  com- 
bination. This  is  why  it  is  used  in  baking.  There 
would  be  less  soda  salt  left  in  the  cake,  etc.,  when  it  is 
neutralized  with  acid  than  if  washing  soda  were  used. 
Sodium  bicarbonate  is  sometimes  known  as  saleratus 
as  well  as  baking  soda. 

An  interesting  development  in  making  alkali  and 
alkali-earth  nitrates  has  been  their  manufacture  from 
air  under  the  influence  of  an  electric  arc  or  spark  from 
platinum  points.  The  manufacture  was  first  started 
at  Niagara  Falls,  but  did  not  succeed,  due  to  poor  con- 
tact of  the'electric  arcs  with  the  air  and  consequently 
low  efficiency  and  waste  of  power.  This  was  in  spite  of 
the  use  of  comparatively  cheap  electrical  power.  (The 
writer  has  been  told  that  power  at  Niagara  Falls  costs 
about  $20-$22  per  horse-power  per  year,  and  at  places 
in  Norway  $9-$10.  An  improved  process  invented  by 
Birkeland  and  Eyde  was  located  in  Norway,  and  is 
making  large  quantities  of  nitrate  of  lime  for  agricul- 


ALKALIES  AND  SALTS  103 

tural  purposes  and  other  products.  To  show  the  result 
of  efficiency  in  chemical  engineering,  as  the  first  process 
tested  at  Niagara  Falls  did  not  pay,  Birkeland  and  Eyde 
extended  the  arcs  by  means  of  electromagnets,  and  in 
that  way  secured  more  surface  to  the  arc  and  more  con- 
tact with  air,  with  consequent  greater  production  of 
nitric  acid.  It  has  been  stated  that  about  120,000  tons 
of  nitrate  and  nitric  products  are  produced  per  year  in 
Norway.  A  nice  contribution  to  industry. 

Of  course,  vast  quantities  of  nitric  acid  in  the  ag- 
gregate are  produced  in  nature  by  lighting  and  are 
carried  into  the  soil  by  the  rain.  Doubtless  nature  still 
produces  more  by  electric  sparks  than  man  does,  and 
both  serve  the  same  purpose  of  stimulating  vegetable 
growth. 

Potassium  in  the  metallic  state  is  very  much  like 
sodium,  and  its  alkaline  compounds  and  salts  are  also 
quite  like  the  corresponding  sodium  compounds.  Po- 
tassium salts  are  in  many  cases  less  soluble  and  less 
deliquescent  (or  water  absorptive).  For  instance,  po- 
tassium nitrate  can  be  used,  along  with  sulphur  and 
charcoal,  for  making  gunpowder,  as  it  does  not  absorb 
water  on  mere  exposure  to  the  air,  and  for  the  same 
reason  potassium  chlorate  is  used  for  match  composi- 
tions, rather  than  sodium  chlorate.  The  great  value 
of  potassium  salts,  or  "potash,"  as  they  are  some- 
times called  in  commerce,  lies  in  the  necessity  for  their 


104  CHEMISTRY  OF  FAMILIAR  THINGS 

use  in  agriculture.    Potash  is  supplied  naturally  from 
the  weathering  of  feldspar,  as  seen  in  Chapter  XII. 

The  chief  commercial  sources  of  potassium  salts 
are  the  great  saline  deposits  at  Stassfurt,  Germany. 
Potassium  chloride  is  the  chief  commercial  salt,  and 
most  other  potassium  salts  are  made  from  it.  Natu- 
ral saline  lakes  in  the  arid  regions  of  Western  United 
States  are  likely  to  prove  a  strong  competitor  to  Ger- 
man potash,  as  the  salt  seems  to  occur,  with  other  sub- 
stances mentioned  on  page  112,  in  almost  unlimited 
quantities.  Seaweed  and  feldspar  have  been  cited 
as  sources  of  commercial  potash,  but  the  expense  of 
extracting  it  from  these  materials  would  seem  to  be 
greater  than  obtaining  it  from  these  saline  deposits, 
which  will  furnish  other  valuable  chemical  substances 
at  the  same  time.  One  can  distinguish  potassium  from 
ordinary  salts  by  putting  a  little  in  a  blue  flame  of  a 
gas  stove  or  alcohol  lamp.  Potassium  colors  it  violet, 
while  sodium  makes  it  yellow.  If  the  two  are  mixed 
one  must  view  the  flame  through  blue  glass,  which  cuts 
out  the  yellow  light,  as  yellow  and  blue  are  comple- 
mentary colors  (see  page  34). 

Ammonium  compounds  are  surprising  substances. 
We  realize  this  even  when  we  have  known  about  them 
for  a  long  time.  Why  nitrogen  when  combined  with 
hydrogen  (NH4)  should  act  just  like  a  metal,  in  that 
it  goes  into  combination  and  comes  out  of  it  intact, 


ALKALIES  AND  SALTS  105 

is  a  strange  circumstance.  It  is  almost  enough  to  make 
one  believe  that  other  metals  are  composite.  But  there 
are  other  reasons  coming  up  of  late  which  indicate  to 
us  that  metals  as  we  know  them  are  not  necessarily 
indivisible  (see  Radium,  page  140  et  seq.). 

Probably  the  chief  value  of  ammonia  lies  in  the  use 
of  the  dry  gas  in  ice-making.  When  the  gas  is  com- 
pressed, heat  is  given  off  and  this  heat  is  absorbed  by 
running  water.  In  the  next  cycle  of  the  process  the 
gas  is  suddenly  released  from  its  compressed  state,  and 
absorbs  large  quantities  of  heat  (creates  intense  cold), 
which  effect  is  communicated  to  other  places  by  means 
of  a  brine,  such  as  salt,  calcium  chloride,  or  magnesium 
chloride  solutions.  These  solutions  remain  liquid  far 
below  the  freezing  point  of  ordinary  water.  Instead 
of  compressing  ammonia  gas  to  a  liquid,  ammonium 
nitrate  has  been  recently  found  useful  in  condensing  it, 
and  the  gas  is  given  off  on  heating  slightly.  Ammonia 
is  also  valuable  for  household  cleaning  in  very  dilute 
solution,  in  the  chemical  laboratory  as  a  mild  alkali 
to  neutralize  acids,  and  as  ammonium  sulphate  in  agri- 
culture. The  danger  of  handling  tanks  of  compressed 
ammonia  is  very  real,  as  they  may  break  from  flaws 
or  careless  handling,  such  as  being  placed  where  it  is  too 
hot.  Escaping  ammonia  gas  will  overcome  and  kill 
those  near  who  cannot  quickly  escape  to  the  outside 
air  or  be  rescued  by  some  one  with  a  respiration  helmet 


106  CHEMISTRY  OF  FAMILIAR  THINGS 

to  supply  the  rescuer  air  for  breathing  while  he  lends 
aid  to  whomever  is  overcome.  This  helmet,  views  of 
which  are  shown  opposite  page  104,  is  also  used  in  coal 
mines  and  wherever  stifling  and  deadly  gas  must  be 
encountered. 

For  agricultural  purposes  large  amounts  of  nitro- 
gen in  some  form  must  be  added  to  the  soil,  as  is  re- 
ferred to  in  Chapter  XII.  As  an  alternative  of  sodium 
nitrate,  from  natural  deposits  in  Chili,  where  several 
million  tons  per  year  are  produced,  and  calcium  nitrate 
(air  saltpetre),  made  in  Norway  from  the  oxidation  of 
the  nitrogen  of  the  air  by  means  of  the  electric  arc,  we 
can  use  ammonia  salts  if  their  price  is  competitive. 
About  1,000,000  tons  per  year  of  nitrogen  in  this  form 
are  produced  each  year  from  the  coking  of  coal  and 
used  largely  in  agriculture.  But  even  this  is  not  enough 
for  the  great  and  growing  demand.  It  has  recently 
been  found  by  Dr.  Haber  and  the  Badische  Aniline  und 
Soda  Fabrik  of  Ludwigshaf  en  am  Ehein,  Germany,  that 
ammonia  can  be  produced  economically  by  the  inter- 
action of  nitrogen  of  the  air  and  hydrogen  under  great 
pressure  at  an  elevated  temperature  and  in  the  presence 
of  a  catalytic  substance,  such  as  iron  oxide.  Certainly 
science  does  not  ignore  the  tiller  of  the  soil,  who  in 
fact  owes  a  great  debt  to  the  chemist.  The  Badische 
Company  have  prepared  themselves  to  make  130,000 
tons  of  ammonium  sulphate  a  year. 


ALKALIES  AND  SALTS  107 

We  now  come  to  the  alkaline- earth  compounds. 
They  were  called  by  that  name  before  chemistry  was  a 
well-developed  science  because  the  oxides  were  sup- 
posed to  resemble  some  form  of  earth  or  clay.  These 
substances  are  important  to  us  because  lime  is  a  member 
of  this  family  and  we  do  so  much  with  lime  (calcium). 

Calcium  is  the  best-known  member  of  this  family, 
and  occurs  native  (in  combination)  as  limestone,  chalk, 
whiting,  coral,  etc.,  which  are  all  composed  of  calcium 
carbonate  (CaC03).  The  free  metal  calcium  itself  has 
been  made  only  in  a  small  way.  It  looks  like  metallic 
sodium.  It  must  be  kept  under  an  hydrocarbon  oil  to 
preserve  it  from  oxidation.  All  skeletons  of  mammalia 
are  made  up  of  calcium  phosphate,  and  large  deposits 
of  phosphate  rock  are  found  which  show  indications  of 
skeletons  of  prehistoric  animals.  This  material  is  used 
for  agricultural  purposes  and  as  a  source  of  phosphorus 
for  matches  and  alloys.  This  is  one  of  the  many  evi- 
dences of  how  nothing  is  lost  in  nature.  Much  of  this 
same  phosphorus  and  lime  may  serve  as  the  skeletons 
and  elements  of  the  tissues  of  successive  generations  of 
mammals. 

Burned  limestone,  or  quicklime,  is  used  for  so  many 
purposes  that  are  well  known,  such  as  making  mortar, 
that  extended  treatment  of  the  subject  is  unnecessary. 
Much  of  the  lime  used  for  mortar  contains  magnesia, 
This  weakens  the  mortar,  but  does  not  necessarily  af- 


108  CHEMISTRY  OF  FAMILIAR  THINGS 

feet  it  seriously  for  masonry.  For  fine,  indoor  plaster- 
ing, it  should  be  made  from  pure  lime.  In  Portland 
cement  manufacture,  magnesia  is  particularly  detri- 
mental. Lime  when  saturated  with  chlorine  forms 
bleaching  powder,  and  when  in  good  fresh  condition 
should  contain  35  per  cent,  of  chlorine  available  for 
bleaching.  Lime  at  a  dazzling  white  heat,  when  fused 
in  the  electric  furnace  with  coke,  makes  calcium  carbide. 
When  water  is  added  to  calcium  carbide,3  acetylene  gas 
is  given  off,  which  burns  brilliantly  and  is  used  for 
isolated  lighting  plants,  automobile  headlights,  and  for 
oxy-acetylene  welding.  Calcium  fluoride  is  a  naturally 
occurring  compound  in  beautiful  yellow  or  violet  crys- 
tals. Hydrofluoric  acid  is  the  gas  that  attacks  and 
etches  glass.  We  have  yet  to  mention  the  useful  com- 
pound of  calcium,  calcium  sulphate,  which  occurs  natu- 
rally as  crystalline  gypsum.  When  gypsum  is  heated  it 
loses  water  of  crystallization  and  becomes  a  powder 
called  plaster  of  Paris.4  In  certain  massive  forms 
gypsum  is  called  alabaster  and  has  been  used  in  carving 
very  fine  pieces  of  sculpture  or  statuettes. 

Having  taken  up  the  most  important  alkaline  earth 
fairly  fully,  we  will  not  have  to  dwell  so  long  on  the 
others.  Barium  is  found  chiefly  as  barium  sulphate, 


8  CaCa  +  HaO  =  CaO  +  C2Ha. 

*  CaSO4  .  2H20  +  heat  =  CaS04  .  iH20  +  1|H2O. 


ALKALIES  AND  SALTS  109 

or  barytes,  and  used  considerably  in  a  levigated  condi- 
tion for  addition  to  white  paint.  It  is  also  made  into 
sulphide  by  heating  with  charcoal.  This  sulphide  is 
phosphorescent  if  kept  in  a  closed  tube,  and  gives  off 
light  in  the  dark  if  it  has  been  previously  exposed  to 
direct  sunlight.  Barium  carbonate  is  found  as  an  ore 
and,  on  heating  strongly,  gives  off  carbon  dioxide  as 
lime  does.  Thus,  barium  oxide  has  the  property  of  tak- 
ing on  excess  of  oxygen  from  the  air  at  a  certain  temper- 
ature, forming  dioxide,  which  gives  off  the  extra  oxy- 
gen at  a  certain  higher  temperature.  This  is  used  as  a 
means  of  making  oxygen.  Barium  dioxide  when  treated 
with  sulphuric  acid  forms  a  valuable  solution, — namely, 
hydrogen  dioxide;  the  by-product  is  barium  sulphate, 
which  can  be  used  as  a  paint  pigment  or  can  be  con- 
verted, by  several  successive  processes,  into  barium 
oxide  again.  Barium  compounds,  especially  the  ni- 
trate, give  a  very  vivid  green  color  to  flame.  This  is 
used  in  fireworks,  etc.  Barium  hydroxide  has  been  used 
as  a  water  softener. 

The  chief  interest  attached  to  strontium  compounds 
is  in  the  use  of  the  hydroxide  in  refining  beet  sugar,  as 
it  forms  a  compound  with  sugar  called  strontium  sac- 
char at  e,  which  enables  one  to  separate  the  pure  sugar 
from  the  beet-root  molasses,  and  sugar  is  subsequently 
freed  from  the  strontium  by  means  of  carbon  dioxide. 


110  CHEMISTRY  OF  FAMILIAR  THINGS 

The  strontium  carbonate  so  formed  is  converted  again 
into  strontium  hydroxide  by  means  of  superheated 
steam. 

Magnesium  resembles  the  alkaline-earth  metals  in 
many  ways.  The  pure  metal  can,  however,  exist  in  or- 
dinarily dry  air  fairly  well,  although  it  combines  with 
the  oxygen  of  the  air  readily  when  a  flame  is  applied. 
It  is  used  for  giving  artificial  light  for  photographic 
purposes.  Magnesium  may  be  obtained  by  electrolysis 
of  the  chloride  or  by  heating  it  with  metallic  sodium. 
It  generally  is  found  in  nature  as  the  carbonate,  and 
when  this  is  heated  it  gives  off  carbon  dioxide  readily 
and  forms  magnesium  oxide,  or  magnesia,  which  is 
used  for  toilet  purposes,  as  an  insulating  material,  and 
in  medicine.  Magnesium  sulphate,  or  Epsom  salts,  was 
first  found  at  Epsom,  England,  in  a  spring  water.  It  is 
much  used  as  a  cathartic.  Magnesium  peroxide  ( Mg02 ) 
is  convenient  for  liberating  active  oxygen.  The  powder 
decomposes  slowly  in  moist  air,  giving  off  oxygen. 

This  little  account  of  chemical  substances  would 
not  be  well  balanced  without  saying  a  few  words  about 
the  so-called  halogens, — fluorine,  chlorine,  bromine,  and 
iodine, — although  they  are  not  important  to  most  people 
who  do  not  expect  to  study  chemistry  systematically. 
They  are  not  familiar  substances  in  themselves,  and 
compounds  of  most  of  them  are  discussed  elsewhere. 


ALKALIES  AND  SALTS  111 

HALOGENS. 
Element  Atomic  weight  Characteristics 

Fluorine 19.  Colorless  gas,  corrosive,  poisonous, 

very  active  chemically. 

Chlorine 35.4  Yellow  gas,  less  corrosive,  active 

chemically  but  less  so  than  flu- 
orine. 

Bromine 80.  Orange-red   liquid,    irritating   but 

less  active  than  first  two;   sub- 
limes. 

Iodine 127.  Steel-blue  solid,  yielding  a  violet 

vapor. 

Bromine  is  very  little  used  except  in  combination, 
being  used  most  as  bromides  in  medicine.  Iodine  is 
chiefly  used  in  medicine  for  local  application  in  al- 
coholic solution  (tincture  of  iodine).  It  will  be  noticed 
how  the  halogens  respond  to  the  principles  of  the  peri- 
odic law.  As  the  molecular  weight  increases  they  be- 
come denser  and  deeper  in  color. 

Sulphur  should  not  be  treated  with  the  alkalies  any 
more  than  the  halogens,  but  there  is  so  little  that  need 
be  said  about  sulphur  in  this  account  of  things  that 
it  can  hardly  be  given  much  space.  Sulphur  occurs 
largely  in  combinations,  such  as  sulphide  of  iron  (py- 
rites), sulphide  of  lead  (galena),  and  sulphide  of  zinc 
(blende),  but,  due  to  volcanic  agencies,  etc.,  it  occurs 
in  a  few  places  as  the  element  sulphur.  It  was  obtained 
almost  exclusively  from  Sicily  until  it  was  found  in 
Louisiana,  where  it  is  melted  in  its  underground  beds 
with  steam  and  brought  to  the  surface  in  pipes.  This 
is  a  great  engineering  triumph. 


112  CHEMISTRY  OF  FAMILIAR  THINGS 

Boron  is  an  element  which  is  used  at  present  only 
in  combination,  as  boric  acid  or  borates,  such  as  borax 
(Na2B407 . 10  H20).  The  ore  used  in  this  country  is 
the  calcium  compound,  or  Colemanite,  found  in  Death 
Valley  and  elsewhere  in  California.  Most  of  it  is 
brought  to  the  vicinity  of  New  York,  where,  by  the  inter- 
action of  soda  ash,  it  is  converted  into  the  sodium  com- 
pound, or  borax.  At  Searles  Lake,  California,  and  else- 
where it  is  found  in  sodium  combination  with  excess  of 
sodium  carbonate  and  potassium  salts.  These  deposits 
seem  to  be  ripe  for  development  and  it  is  to  be  hoped 
especially  that  an  abundance  of  potassium  salts  will 
be  produced  from  such  sources.  Borax  is  valuable  as  a 
mild  alkali,  and  useful  in  the  household  for  bathing  and 
cleaning  clothes,  dishes,  etc.  It  softens  water  and 
neutralizes  acids. 


PLATE   VIII. 


Courtesy  of  Union  Sulphur  Company. 

Pumping  sulphur  into  storage  bins  in  Louisiana  (Frasch  Process). 


Courtesy  of  Richard  K.  Meade. 

Rotary  furnace  for  the  continuous  burning  of  cement  rock. 


CHAPTER  IX 

METALS 

MANY  people  consider  metals  as  strong,  hard,  tough 
substances,  but  the  metals  sodium,  potassium,  etc., 
treated  in  the  last  chapter,  are  soft  and  others  are 
brittle.  Those  described  at  greatest  length  here,  how- 
ever, are  the  toughest  and  strongest. 

Metals  are  so  varied  in  physical  properties  that 
there  cannot  be  any  uniform  description  except  as  to 
the  so-called  metallic  lustre  they  possess.  At  ordinary 
temperature  hydrogen  is  a  gas  that  burns  to  form  water 
vapor  with  oxygen,  and  few  would  think  of  it  as  a 
metal.  Yet  it  oxidizes  like  the  metals,  it  unites  with 
chlorine  like  metals,  and  when  chilled  with  liquid  air  it 
first  becomes  liquid  and  then  solidifies  and  looks  like 
silver  or  lead.  Hydrogen,  for  reasons  of  convenience, 
is  usually  treated  in  books  with  the  non-metals.  We 
really  have  metals  as  gases  like  hydrogen,  liquids  like 
mercury,  and  solids  like  iron.  Iron  and  other  metals 
which  are  solid  at  ordinary  temperatures  can  be  lique- 
fied by  heat,  and  at  higher  temperatures  will  volatilize. 

The  substances  found  in  the  earth  from  which 
metals  are  obtained  are  called  ores.  If  they  contain 
sulphur  or  carbon  dioxide  in  combination,  as  most  of 
8  113 


114  CHEMISTRY  OF  FAMILIAR  THINGS 

them  do,  they  are  first  roasted  to  obtain  the  oxides. 
Oxides  are  then  converted  into  their  respective  metals 
by  smelting  or  heating  to  high  temperatures  with  car- 
bon (coke  or  charcoal),  frequently  in  the  presence  of 
lime,  to  slag  with  the  silica,  present  as  an  impurity. 

Most  metals  tend  to  revert  to  their  oxides,  which 
happening  governs  the  usefulness  of  most  of  them.  The 
so-called  noble  metals — silver,  gold,  platinum,  and  a 
few  very  rare  ones,  such  as  iridium — do  not  tend  to 
oxidize  even  on  heating  to  high  temperatures  with  ac- 
cess of  air.  This  means  they  do  not  tarnish  easily,  and 
it  gives  them  special  value. 

A  great  many  chemical  and  metallurgical  plants 
send  off  gases  that  may  in  some  cases  be  deleterious  to 
man  and  certainly  are  ruinous  to  vegetation.  Acid 
fumes  kill  vegetation,  and  fine  dust  blights  or  kills  it. 
With  acid  gases  the  effort  is  now  generally  made  to 
utilize  them  in  some  way  rather  than  to  liberate  them. 
Sulphur  dioxide  gas  (sulphurous  acid)  is  now  made 
into  sulphuric  acid,  while  some  time  ago  it  was  wasted 
from  almost  all  smelters.  Eecently  Professor  F.  G. 
Cottrell  and  associates  devised  and  developed  an  in- 
genious process  for  removing  fine  dust  and  otherwise 
uncondensable  vapors  issuing  from  manufacturing 
plants  and  smelters.  It  was  found  that  a  very  high 
tension  direct  current  of  from  15,000  to  45,000  volts, 
silently  discharging  from  electrodes  in  a  smoky  or  va- 


PLATE   IX. 


Courtesy  of  the  Research  Corporation. 

Fumes  from  stacks  before  turning  on  high  voltage  current. 


After  turning  on  current.     Note  absence  of  smoke.     Cottrell  process  for  fume  precipitatic 


METALS  115 

porous  atmosphere,  caused  the  particles  to  coalesce 
and  fall  by  gravity.  This  process  will  prove  of  great 
value  in  regions  troubled  by  fine  dust  and  acid  vapors 
from  smelters.  Much  of  this  dust  is  rich  in  arsenic  and 
is  not  desirable  as  a  substitute  for  snow.  This  process 
also  applies  to  black  smoke,  from  which  it  will  remove 
the  soot  if  properly  applied.  Thousands  of  tons  of  car- 
bon soot  fall  in  Pittsburg  and  suburbs  every  year,  and 
some  such  process  ought  to  be  put  into  application  very 
promptly  in  the  Pittsburg  district  and  many  other 
places  as  well. 

Iron  (Fe)  is  one  of  the  greatest  gift§  of  nature  to 
man,  and  with  its  use  man  has  fought  and  worked  his 
way  onward  and  harnessed  the  great  forces  of  nature 
for  his  benefit.  Iron  production  shows  to  advantage 
the  progressive  spirit  that  has  given  this  country  such 
a  marvellous  growth,  and  the  recent  development  in 
other  countries  has  been  most  marked  by  improvements 
in  the  production  of  iron,  steel,  and  their  manufac- 
tured articles. 

Iron  ore  (essentially  iron  oxide,  hematite,  Fe203)  in 
some  localities  is  mined  with  steam  scoop  shovels  and 
dumped  at  once  into  cars,  which  in  many  cases  are 
picked  up  bodily  and  their  contents  dumped  into  the 
holds  of  boats.  At  the  blast-furnace  where  the  iron  is 
made  everything  is  handled  by  travelling  cranes,  etc. 
The  charge  in  the  blast-furnace  is  composed  of  lime 


116  CHEMISTRY  OF  FAMILIAR  THINGS 

(CaO),  iron  ore  (Fe203),  and  coke  (C).  These  are 
dumped  in  layers  at  the  top  of  the  blast-furnace  through 
a  hopper,  and  a  cover  called  a  bell  closes  over  the  charge. 
Air  heated  by  gases  from  the  furnace  is  used  to  force 
the  combustion.  The  air  is  first  freed  of  moisture  by 
refrigeration,  the  invention  of  James  Gayley.  Chemists 
and  engineers  were  at  first  inclined  to  doubt  the  ef- 
ficacy of  this  additional  step  in  the  process,  but  a  short 
time  of  use  has  amply  justified  Gayley ys  idea.  The 
power  for  this  refrigeration,  the  heating,  and  the  blow- 
ing comes  from  the  gases  of  the  furnace,  which  are 
tapped  off  and  used  in  gas-engines.  The  action  in  this 
furnace  is  essentially :  Carbon  reduces  the  iron  and  lime 
makes  a  fusible  slag  or  kind  of  glass  with  the  silica, 
present  as  impurity  in  the  ore.1  This  pig-iron  from  the 
blast-furnace  always  contains  dissolved  carbon,  phos- 
phorus, and  silicon,  and  it  is  purified,  on  being  made  into 
steel  or  wrought  iron,  by  blowing  air  through  it  while 
at  a  white  heat,  which  oxidizes  the  silicon  and  carbon 
so  that  they  can  be  removed  by  lime.  This  is  the  action 
of  the  Bessemer  converter.  The  open-hearth  furnace 
does  similar  work  by  heating  the  iron  which  contains 
the  silicon  in  the  presence  of  air  and  lime.  The  oxygen 
of  the  air  (or  some  supplied  by  means  of  iron  oxide) 
changes  the  silicon,  phosphorus,  and  carbon  into  oxides, 

1  Fea03  +  30  =  Fea  +  SCO. 


PLATE  X. 


Courtesy  of  Dr.  E.  F.  Roet 


Heroult  electric  steel  furnace. 


METALS  117 

and  the  lime  neutralizes  and  separates  them  from  the 
metal. 

There  have  been  a  great  many  improvements  re- 
cently in  the  production  of  iron  and  its  alloys.  Pure  mal- 
leable iron  has  recently  been  made  electrolytically.  Ear- 
lier attempts  to  make  pure  iron  electrolytically  gave  a 
brittle  alloy  of  iron  with  hydrogen.  By  alloying  iron 
with  an  excess  of  chromium  and  a  little  molybdenum  an 
alloy  is  obtained  that  resists  nearly  all  acids,  even  when 
concentrated.  Steels  have  been  made  for  safes  that  it 
is  claimed  cannot  be  drilled  or  exploded  even  by  those 
adept  in  the  art. 

The  highest  degree  of  refinement  in  the  making  of 
steel  is  attained  by  heating  it  electrically  while  lime  is 
thrown  into  it  to  remove  phosphorus,  which  cannot  be 
taken  out  as  thoroughly  in  the  converter  or  open-hearth 
furnace.  This  makes  steel  which  is  stronger  and 
denser  than  ordinary  steel.  Steel  contains  a  little  com- 
bined carbon,  but  no  admixed  or  graphitic  carbon,  as 
does  cast  iron.  In  tempering  steel  it  is  heated  to  red- 
ness and  plunged  into  water.  This  makes  it  very  hard, 
but  it  must  then  be  heated  up  to  a  moderate  heat,  but  not 
to  redness,  to  toughen  it.  The  latter  process  is  anneal- 
ing. In  recent  years  the  microscope  and  affixed  camera 
have  been  introduced  for  examining  and  recording  the 
appearance  of  polished  sections  of  metal.  Much  light 


118  CHEMISTRY  OF  FAMILIAR  THINGS 

has  thus  been  thrown  on  the  wearing  away  of  rails  used 
for  transportation  purposes. 

The  accompanying  illustrations  opposite  pages  118 
and  120,  for  which  the  author  is  indebted  to  Professor 
Albert  Sauveur,  show  the  micro-structure  of  different 
kinds  of  iron  and  steel.  It  can  readily  be  seen  how  the 
character  of  metal  to  be  subjected  to  great  physical 
strain  can  be  ascertained  before  use.  "When  metal,  such 
as  a  defective  rail  or  steel  work  of  a  bridge,  gives  way, 
photomicrographs  will  show  the  reason  if  the  steel  is 
defective  or  unsuitable  for  the  purpose.  The  chief  de- 
sideratum is  to  have  steel  as  homogeneous  as  possible, 
so  that  the  parts  of  the  metal  are  continuous  through- 
out, and  not  have  particles  of  iron  sulphide,  iron  oxide, 
or  carbon,  etc.,  between  the  steel  particles.  To  minimize 
corrosion  of  iron  or  steel  it  is  also  desirable  to  have  the 
metal  uniform  throughout,  and  photomicrographs  will 
show  this  condition.  Cuts  1  to  6  show  different  kinds 
of  steel ;  of  course  they  look  much  more  dissimilar  under 
the  lenses  than  to  the  unaided  eye,  but  the  different 
ways  these  metals  would  act  in  use  are  quite  as  va- 
rious as  the  pictures.  Cuts  7  and  8  show  two  important 
kinds  of  cast  iron.  Number  8  has  less  metal  between 
the  iron  particles,  so  that  it  is  stronger  than  the  gray 
iron. 

The  corrosion  or  rusting  of  iron  and  steel  is  a  matter 
of  considerable  economic  importance,  and  seems  to  the 


PLATE  XI. 


-;7. 


•*;<M% 


Courtesy  of  Prof.  Albert  Sauveur. 

1.  Soft  steel— 0.10  per  cent,   carbon. 
100  Diams. 


2.   Steel  about  0.30  per  cent,  carbon. 
100  Diams. 


3.   Steel  about  0.50  per  cent,  carbon. 
100  Diama. 


4.   Steel  eutectoid,  0.85  per  cent,  carbon. 
400  Diams.  (note  homogeneity). 


METALS  119 

writer  of  sufficient  general  interest  to  treat  of  in  this 
book.  Some  people  have  noticed  that  iron  or,  more  par- 
ticularly, steel  articles  corrode  more  readily  than  they 
did  a  generation  ago.  If  this  observation  be  correct — 
and  it  probably  is — the  difference  is  due  to  the  substitu- 
tion of  steel  (with  its  impurities)  for  pure  wrought 
iron.  Wrought  iron  used  to  be  made  more  readily  than 
steel  and  for  many  purposes  was  better  than  steel.  Now 
comparatively  little  wrought  iron  is  made,  but  steel  is 
supplied  in  its  place.  Steel  is  made  first,  and  the  soft 
steel  or  iron,  when  finally  made  by  continuing  the  proc- 
ess, does  not  seem  to  be  as  good  for  tinning,  fence  wire, 
etc.,  as  the  old-fashioned  wrought  iron. 

Pure  iron  does  not  rust  with  water  alone  or  with 
water  and  oxygen.  It  is  only  when  carbon  dioxide  is 
present  that  iron  rusts.2  But  as  carbon  dioxide  is  al- 
ways present  in  the  air  and  in  most  natural  waters,  it 
is  not  unusual  to  have  conditions  suitable  for  rust 
formation.  It  will  be  seen  from  the  reactions  in  the  foot- 
note that  the  rusting  of  pure  iron  takes  place  in  two 
stages.  Generally  one  does  not  note  the  formation  of 
bicarbonate,  as  the  carbon  dioxide  gas  is  not  in  evi- 
dence, but  when  the  carbon  dioxide  acts  with  partial 

2  (a)  Iron  +  carbon  dioxide  +  water  +  oxygen  =  bicarbonate  of  iron 

Fe2  4C02  2H20          O2  2FeH2(CO3)a 

(b)   Bicarbonate  +  oxygen  -f-  water  =  iron  rust  +  carbon  dioxide 

of  iron 
2FeH2(CO3)a        0  H20       2Fe(OH)a  4COa 


120  CHEMISTRY  OF  FAMILIAR  THINGS 

exclusion  of  air  the  bicarbonafe  of  iron  goes  into  solu- 
tion, and  then,  when  aerated,  the  water  becomes  red 
with  ferric  hydroxide  (iron  dust).  Many  underground 
waters  contain  colorless  bicarbonate  of  iron,  which 
is  turned  to  ferric  hydroxide  (red)  by  action  of  the  air. 
Cast  iron  and  steel  are  not  pure  iron  and  they  rust 
more  readily,  due  to  galvanic  action  set  up  by  the  im- 
purities, and  carbon  dioxide  is  not  requisite,  although 
cast  iron  has  a  silicious,  rust-resisting  coating  when  new. 
The  impurities  in  cast  iron  and  steel,  such  as  carbon, 
sulphur,  manganese  dioxide,  mill  scale  (in  rolled  steel), 
etc.,  are  electronegative  to  iron,  and  if  water  be  present 
oxygen  forms  on  the  iron,  unites  with  it,  and  makes 
oxide  or  hydroxide.  Hydrogen  is  evolved  from  the  elec- 
tronegative particles  (generally  of  microscopic  fine- 
ness). Dilute  acids  promote  corrosion  by  making  elec- 
trically conductive  battery  fluids  to  facilitate  the 
chemical  action  of  the  iron  and  the  non-iron  particles. 
Acid  salts  and  neutral  salts  (alum,  table  salt,  etc.)  act 
similarly,  but  alkaline  salts  and  alkalies  (borax,  wash- 
ing soda,  etc.)  retard  or  prevent  corrosion.  The  purest 
iron  and  the  purest  steel  corrode  least  readily.  In 
cases  of  solution  of  iron,  water  is  necessary  as  well  as 
acid,  and  anhydrous  acids  do  not  dissolve  metals  at 
all.  For  instance,  concentrated  sulphuric  acid  may  be 
stored  in  steel  tanks  and  transported  in  steel  tank  cars. 
A  very  little  copper  is  sometimes  added  to  steel,  which 


PLATE  XII. 


Courtesy  of  Prof.  Albert  Sauveur. 

5.   Steel  hypereutectoid,   1.10  per  cent, 
carbon.      100  Diams 


5.  High    carbon,    hardened    steel.      100 
Diams. 


7.  Gray    cast   iron,   No.   2    foundry. 
Diams. 


100 


8.   White  cast  iron.      100  Diams. 


METALS  121 

is  supposed  to  make  it  more  resistant  to  corrosion,  but 
the  best  solution  probably  lies  in  absolute  purity. 

While  alkalies  protect  iron  from  corrosion,  they 
cannot  be  employed  often  for  that  purpose,  except  that 
the  cement  coating  much  used  on  steel  girders,  etc.,  is, 
in  a  way,  alkaline  in  reaction.  Zinc  coatings  protect 
iron  from  corrosion,  as  explained  on  page  125.  Nickel, 
copper,  and  tin  protect  iron  only  when  they  completely 
cover  it,  as  they  are  electronegative  to  iron,  like  the 
particles  of  sulphur,  carbon,  etc.,  in  steel,  and  broken 
surfaces  in  the  presence  of  moisture  facilitate  corrosion 
of  the  iron. 

Another  phase  of  this  subject  is  the  electrolytic  cor- 
rosion of  underground  pipes  due  to  stray  electricity 
from  street  railways  using  them  as  conductors,  because 
of  the  less  resistance  of  iron  than  damp  earth.  Where 
the  current  enters  the  iron  (cathode)  hydrogen  is 
evolved,  which  does  not  act  chemically  on  the  iron,  and 
alkali  is  formed,  which  protects  it ;  but  where  the  cur- 
rent leaves  the  iron  (anode)  oxygen  is  evolved,  which 
causes  corrosion,  due  to  the  influence  of  oxygen  and  free 
acid  that  is  formed.  With  lead  cables  the  opposite 
seems  to  happen.  The  cathode  pole  corrodes,  due 
to  the  alternate  alloying  of  hydrogen  with  lead,  and  the 
chemical  action  of  oxygen  in  the  soil  causes  the  forma- 
tion of  lead  oxide.  Remedies  for  these  troubles  have 
been  found  by  engineers.  Pipes  are  bonded  to  the  rails 


122  CHEMISTRY  OF  FAMILIAR  THINGS 

of  the  electric  lines  in  some  cases,  and  in  others  zinc 
is  fastened  to  the  pipes  or  other  underground  iron  work, 
which  acts  like  the  galvanizing  directly  on  the  metal 
by  giving  up  itself  to  electrolytic  corrosion  instead  of 
the  iron  or  steel. 

Aluminum  (Al)  has  been  referred  to  as  being 
present  in  the  soil  in  predominant  quantity  as  clay. 
Aluminum,  as  metal,  cannot,  however,  be  readily  ex- 
tracted from  clay,  and  it  was  not  made  economically 
until  a  way  was  found  to  make  it  from  alumina,  pro- 
duced from  the  mineral  bauxite,  a  hydroxide  of  alumi- 
num and  iron. 

The  writer  remembers,  when  a  boy,  seeing  aluminum 
when  it  cost  $20  per  pound,  whereas  it  is  now  sold  for 
about  18  cents  per  pound.  The  great  step  forward  was 
made  by  Charles  M.  Hall  when  just  out  of  college.  He 
dissolves  alumina  (the  oxide  of  aluminum)  in  molten 
cryolite,  which  latter  is  a  double  flue-ride  of  sodium 
and  aluminum,  and  then  electrolyzes  3  the  mass,  de- 
positing aluminum  as  molten  metal  on  the  negative 
pole,  which  consists  of  iron,  while  carbon  serves  as  the 
positive  pole.  Alumina  is  piled  above  each  furnace  and 
dissolves  in  the  molten  cryolite  as  fast  as  required. 

Aluminum  is  the  lightest  metal  that  is  reasonably 
stable  in  the  air.  One  of  the  greatest  uses  for  the  metal 
now  is  for  stamping  out  all  kinds  of  utensils  for  the 

8  2A12O3  ( +  electricity)  =  2A12  +  30* 


METALS  123 

kitchen  and  home  and  small  articles  generally.  These 
vessels  are  very  little  attacked  by  vegetable  acids,  etc., 
in  use,  and  any  white  tarnish  that  forms  is  harmless. 
Aluminum  tarnishes  or  becomes  corroded  by  overheat- 
ing, and  rubbing  with  a  silica  powder  or  silica  soap  is 
generally  necessary  to  polish  it.  Aluminum  is  more  re- 
sistant to  acids  than  it  is  to  alkalies.  It  has  been  intro- 
duced for  lining  tanks  for  the  transportation  of  nitric 
acid  in  bulk.  Aluminum  should  not  be  used  for  alka- 
line solutions ;  even  ordinary  alkali  carbonates  attack  it. 
Aluminum  is  much  used  as  wire  for  carrying  heavy 
electrical  currents,  as  it  will  carry  more  current  than 
copper  for  equal  weights.  Its  use  is  governed  generally 
by  the  price  of  copper,  which  fluctuates  considerably. 
Its  lightness  renders  it  valuable  for  automobile,  motor- 
boat,  and  aeroplane  construction.  Finely  powdered 
aluminum  is  used  as  paint  pigment  for  radiators,  pipes, 
and  painting  metal  surfaces.  It  is  also  used  in  flash 
powder,  as  it  is  easily  burned  by  oxidizing  agents  that 
are  intermixed  intimately  and  gives  a  brilliant  light.  A 
somewhat  similar  reaction  happens  in  the  Thermit  proc- 
ess, in  which  an  oxide,  such  as  iron  oxide,  is  mixed  with 
powdered  aluminum.  The  aluminum  has  more  affinity 
for  the  oxygen  than  the  iron,  and  when  the  mixture  is 
touched  off  by  a  fuse  there  is  a  large  amount  of  heat 
liberated,  a  brilliant  light  is  created,  and  molten  iron  or 
steel  is  formed,  which  is  run  into  moulds  to  repair 


124  CHEMISTRY  OF  FAMILIAR  THINGS] 

breaks  in  iron  or  steel  castings,  etc.  This  same  process 
has  been  used  successfully  for  producing  many  metals 
in  the  pure  state,  such  as  tungsten. 

Aluminum  salts  are  used  as  mordants  and  for  many 
other  purposes.  The  chief  salt  is  aluminum  sulphate  or 
concentrated  alum  (A12(S04)3  +  15H20),  and  differs 
from  common  alum  in  not  having  any  alkaline  sulphate 
crystallized  with  the  aluminum  sulphate ;  consequently, 
it  is  more  concentrated  in  active  principle,  as  the 
alkaline  salt  is  inert.  Fused  alumina  (A1203)  is  used 
as  an  abrasive  and  to  make  crucibles,  etc.,  for  the 
laboratory. 

Zinc,  (Zn)  has  been  used  as  a  metal  for  several  hun- 
dred years,  and  from  very  ancient  times  alloyed  with 
copper  as  brass.  It  seems  rather  strange  that  it  should 
be  known  in  the  alloy  form  before  it  was  known  as  pure 
metal,  and  it  would  seem  as  if  copper  was  thought  neces- 
sary in  the  reduction  of  the  metal.  The  chief  ores  of 
zinc  found  in  the  United  States  are  zinc  sulphide,  zinc 
silicate,  and  a  composite  mineral,  called  franklinite, 
composed  of  zinc,  iron,  and  manganese  oxides.  As  the 
sulphide,  or  "zinc  blende,"  is  the  predominant  ore,  we 
will  briefly  refer  to  its  use.  The  ore  is  freed  mechan- 
ically as  well  as  possible  from  silicious  matters  called 
gangue,  and  then  roasted  at  a  high  temperature  in  the 
presence  of  air  to  form  the  oxide.  This  oxide  of  zinc  is 


METALS  125 

distilled  4  in  relatively  small  clay  retorts  with  coke  and 
the  zinc  vapor  condensed.  A  commercial  plant  has 
rows  of  such  retorts  with  the  cooler  ends  and  condenser 
sticking  out  of  the  furnace  walls.  Bluish-white  flames 
flicker  at  each  retort  where  incandescent  zinc  vapor  is 
burning  as  it  leaks  out.  It  is  now  proposed  to  reduce 
and  distil  zinc  in  large  furnaces  by  means  of  elec- 
trically produced  heat. 

Zinc  is  used  in  alloys,  to  most  of  which,  like  brass,  it 
gives  hardness.  Like  copper,  it  is  employed  in  sheet 
metal  for  exposed  places,  as  it  does  not  corrode  se- 
riously with  water.  It  is  used,  however,  mostly  as  coat- 
ings on  steel  sheets  or  cast-iron  objects  (called  gal- 
vanized iron),  which  it  protects  perfectly  so  long  as 
the  underlying  metal  is  covered.  Even  when  only 
partly  covered,  it  protects  for  quite  a  while  by  galvanic 
or  electrolytic  action  from  the  rust-producing  effect 
of  moist  air.  This  is  because  zinc  tends  to  corrode 
rather  than  iron,  and  slowly  wears  away,  leaving  the 
iron  free  from  rust,  until  very  little  zinc  is  present. 
Copper  in  contact  with  iron,  galvanized  iron,  or  zinc 
causes  corrosion  of  these  metals.  Brass,  which  is  an 
alloy  of  metals  with  opposite  electrical  properties,  hap- 
pens to  be  nearly  electrically  neutral  to  iron.  Brass 
rich  in  copper,  or  red  brass,  acts  somewhat  as  a  galvanic 


126  CHEMISTRY  OF  FAMILIAR  THINGS 

couple  with   iron,   because   of   the   predominance   of 
copper. 

Zinc  oxide  (ZnO)  is  probably  the  most  valuable 
product  of  zinc  other  than  the  metal,  and  is  used  as  a 
pigment  in  paints  with  or  without  white  lead.  It  covers 
better  than  white  lead,  and  it  does  not  seem  to  have 
as  much  tendency  to  chalk  off  as  white  lead,  and 
is  not  discolored  by  hydrogen  sulphide.  The  best 
article,  the  writer  believes,  has  both  present.  Zinc 
chloride  is  a  soluble  salt  of  zinc  which  is  used  for  im- 
pregnating wood  to  prevent  decay.  Zinc  sulphate  is 
used  for  making  many  chemical  substances  and  in  the 
arts. 

Copper  (Cu)  occurs  in  nature  chiefly  as  native 
copper,  the  sulphide,  and  the  carbonate.  Near  the  sur 
face  of  the  ground  in  copper-mining  districts,  car- 
bonate of  this  metal  is  found,  but  the  most  of  the  ore 
mined  is  sulphide,  which  is  found  in  strata  below  the 
carbonate.  The  smelting  of  copper  is  very  complicated 
and  it  would  take  a  good  deal  of  space  to  treat  the 
matter  fully.  It  is,  essentially,  a  heating 5  of  copper 
oxide  and  sulphide  in  closed  furnaces.  Most  copper, 
is  not  a  finished,  manufactured  article  now  until  the 
smelted  product  is  refined  electrolytically.  In  this 
operation  copper  is  dissolved  at  the  anode,  or  positive 

B2CuS  -f  02  =  Cu2S  +  SO2. 
2CuO  -1-  Cu2S  =  4Cu   +  S02. 


METALS  127 

pole,  and  is  precipitated  quite  pure  at  the  cathode,  or 
negative  pole,  of  an  electrolytic  cell.  Silver  and  any 
gold  in  the  crude  articles  are  caught  as  a  sludge  and 
refined  separately. 

Copper  is  valuable  for  its  ductility,  malleability, 
toughness,  and  non-corrosive  character.  It  tarnishes, 
but  this  skin  of  altered  metal  protects  the  body  of  the 
metal.  It  is  alloyed  with  gold  and  silver  in  coins,  and 
with  other  metals  in  bronzes.6  Copper  is  used  for  roof- 
ing, gutters,  and  flashings  on  roofs,  because  it  only 
tarnishes  and  does  not  wear  away  very  fast.  Copper 
"«  not  affected  by  weak  acids,  such  as  are  in  foods,  so 
t  can  be  used  for  cooking  vessels.  These  must  be  kept 
try  and  polished,  as  a  little  water  on  contact  with  air 
ill  cause  the  formation  of  a  green  film  of  basic 
Copper  carbonate.  Ammonia  dissolves  copper  in  the 
presence  of  air,  forming  a  blue  solution  which  will  dis- 
solve cellulose.  Copper  plating  on  iron  by  means  of 
electricity  is  sometimes  practised,  and  a  cyanide  bath 
must  be  used.  If  clean  iron  is  merely  dipped  into  copper 
sulphate  it  is  covered  with  a  coating  of  copper,  but  it  is 
so  thin  that  it  is  no  protection  to  the  iron,  and,  in  fact,  it 
is  apt  to  make  the  iron  rust  by  galvanic  action. 

"Alloy                           Copper  Tin  Zinc 

Brass    66  ..  34 

Bronze 84  10  6 

Gun-metal     90  . .  10 

U.  S.  Cent                 ..95  2  3 


128  CHEMISTRY  OF  FAMILIAR  THINGS 

The  chief  copper  salt  is  the  sulphate  called  "blue 
vitriol,"  and  is  used  to  make  insecticides  such  as  Paris 
green,  copper  arsenate,  and  Bordeaux  mixture,  which 
is  copper  hydroxide  precipitated  from  the  sulphate  by 
means  of  milk  of  lime. 

Lead  (Pb)  is  generally  found  as  the  sulphide,  called 
galena,  and  is  smelted  much  like  copper  by  first  roasting 
and  then  heating  in  the  absence  of  both  air  and  car- 
bon. Most  metal  ores  are  roasted  to  oxide  and  then 
reduced  with  carbon  to  the  metallic  state,  but  lead  and 
copper  are  roasted  just  enough  to  make  a  partial  oxida- 
tion and  then  this  oxide  acts  on  the  unchanged  sulphide. 
Lead  is  soft,  tough,  melts  at  a  low  temperature,  and  is 
not  attacked  readily  by  acids  or  other  chemicals.  These 
properties  give  it  wide  usefulness  for  piping  connec- 
tions and  lining  tanks,  making  plates  for  storage  bat- 
teries, etc. 

Lead  is  corroded  by  the  joint  action  of  acetic-acid 
vapors  and  carbon-dioxide  gas  to  form  white  lead,  or 
basic  carbonate  (2PbC03 .  Pb(OH2) ).  Lead  also  forms 
the  yellow  color,  lead  chromate. 

Mercury  (quicksilver,  Hg)  is  the  only  metal  that  is 
liquid  at  the  ordinary  temperature.  It  is  found  as  the 
sulphide,  or  cinnabar  (HgS),  in  Spain,  California, 
Texas,  and  elsewhere.  Merely  heating  this  ore  causes 
mercury  to  separate  from  sulphur.  Both  distil,  the 
mercury  is  condensed,  while  the  sulphur  combines  with 


METALS  129 

oxygen  to  form  sulphur  dioxide  gas.  Mercury  is  not 
produced  in  as  great  quantities  as  most  other  metals,  as 
the  uses  for  it  are  more  limited  and  where  it  is  used  it 
is  not  consumed  very  fast;  for  instance,  in  making 
thermometers,  in  electrolytic  production  of  sodium  hy- 
droxide, and  in  the  recovery  of  gold  from  admixture 
with  silica  and  clay.  Mercury  is  over  thirteen  times 
as  heavy  as  water.  A  small  jar  holding  a  pint  would 
weigh  about  13.9  pounds. 

If  some  mercury  is  put  into  a  dilute  silver  nitrate 
solution,  an  interesting  action  ensues.  The  mercury 
has  a  greater  affinity  for  the  nitric  acid  radicle  than 
the  silver,  so  it  goes  into  solution,  and  the  silver  is  pre- 
cipitated and  at  once  unites  with  the  excess  of  mercury 
to  form  an  alloy,  which  crystallizes  quite  beautifully 
in  arborescent  shapes,  known  to  the  alchemists  as 
"Arbor  Dianse."  (See  page  19.) 

Tin  (Sn)  is  a  metal  that  is  useful  in  its  protective 
influence  on  other  metals.  This  protective  influence  is 
rather  over-estimated,  however,  in  many  cases.  A  uni- 
form and  fairly  thick  coating  would  protect  steel  sheets, 
for  instance,  but  what  is  put  on  is  often  not  a  uniform 
coating.  There  generally  exist  minute  pores  in  tin 
plate,  due  to  impurities  in  the  sheets,  which  the  tin  does 
not  fully  coat.  Eoofing  tin  plate  is  generally  com- 
posed of  a  tin-lead  alloy,  called  terne  plate,  and  usually 

contains  a  distinctly  minor  percentage  of  tin.    Solder 
9 


130  CHEMISTRY  OF  FAMILIAR  THINGS 

is  also  a  tin-lead  alloy.  Pure  tin  piping  is  much  used 
for  water-pipes  in  high-grade  water-filters,  in  condens- 
ing worms,  etc.  Tin-foil  is  often  tin-lead,  but  for  coat- 
ing foods,  such  as  cheese,  chocolate,  etc.,  it  should  be 
made  of  pure  tin,  because  of  the  poisonous  action  of 
the  lead. 

'Nickel  (Ni)  somewhat  resembles  iron,  although  it  is 
not  so  easily  corroded.  Most  of  the  nickel  we  use  is 
from  Canadian  ores.  Nickel  is  smelted  somewhat  like 
copper,  but  is  refined  by  an  ingenious  process  devised 
by  Ludwig  Mond,  an  English  chemist.  Carbon  mon- 
oxide (producer  gas)  is  blown  through  the  moderately 
hot  metal,  and  this  volatilizes  the  nickel  and  removes 
it  from  the  impurities.  When  at  a  slightly  higher  tem- 
perature the  gas  is  made  to  give  up  the  nickel.  Some 
nickel  is  smelted  directly  with  copper  that  was  asso- 
ciated with  it  in  the  ore,  and  this  makes  Monel  metal. 
Monel  metal  takes  valuable  properties  from  both  the 
nickel  and  the  copper.  It  is  tougher  than  nickel  and 
stronger  than  copper.  It  is  not  easily  corroded  and  is 
used  for  fly-screens,  which  are  very  satisfactory. 
Nickel  coin  in  this  country  contains  copper,  50  per  cent., 
and  nickel,  25  per  cent.  Monel  metal  consists  of  copper 
40  and  nickel  60  per  cent. 

Manganese  (Mn)  is  a  metal  that  has  been  known  for 
a  good  while  and  has  been  used  in  steel  to  strengthen  it. 
Of  the  salts,  potassium  permanganate  is  the  best  known 


METALS  131 

and  is  used  as  an  oxidizing  agent.  A  dilute  solution  of 
this  is  sometimes  used  as  an  antiseptic. 

Manganese  dioxide  (Mn02)  is  a  valuable  oxidizing 
agent  used  as  drier  for  oils  and  in  dry-cell  electric  bat- 
teries to  absorb  nascent  hydrogen  around  the  carbons. 
This  action  is  called  depolarization  and  the  manganese 
dioxide  is  therefore  called  a  depolarizer. 

Chromium  (Cr)  is  obtained  as  an  oxide  usually  as- 
sociated with  iron  as  chrome  iron  ore.  The  metal  is 
used  to  make  chrome  steel,  but  is  chiefly  used  to  form 
salts  or  chromates  such  as  have  been  referred  to  under 
sodium  salts  and  under  lead. 

Tungsten  (W)  is  found  in  reasonable  quantities  in 
the  Western  States,  chiefly  as  the  mineral  wolframite, 
or  iron  tungstate  (FeWOJ.  The  metal  itself  has  only 
recently  been  made  pure  enough  to  draw  out  in  the 
wire  for  electric  lamps.  This  wire  is  drawn  through 
diamond  dies  as  small  as  1/40  millimetre.  Tungsten 
is  used  for  these  filaments  because  of  its  high  melting 
point.  Tungsten  is  also  much  used  in  small  percentages 
to  harden  steel. 

Vanadium  (V)  is  used  like  tungsten  to  make  a 
special  steel  which  is  very  tough  and  strong. 

Thorium  (Th)  is  a  rare  element  obtained  from  mona- 
zite  sand,  found  principally  in  the  mouths  of  rivers  on 
the  coast  of  North  Carolina.  There  are  other  rare  ele- 
ments also  present  in  this  sand.  Thorium  is  converted 


132  CHEMISTRY  OF  FAMILIAR  THINGS 

into  nitrate  (Th(NO3)4)  and  then  into  oxide  when  the 
incandescent  gas-mantle  filaments  are  made.  The 
mantles,  when  the  cementing  pyroxylin  lacquer  is 
burned  off,  consist  of  about  98  per  cent,  thorium  oxide 
to  2  per  cent,  cerium  oxide. 

Cerium  (Ce)  is  another  so-called  rare  earth  metal, 
the  oxide  of  which  is  produced  from  monazite  sand  to  be 
used  with  thorium  oxide  for  incandescent  mantles.  The 
metal  itself  is  also  produced  and  is  alloyed  with  iron 
to  make  a  sparking  gas  lighter  used  in  place  of  matches 
by  rubbing  on  a  short  steel  file. 

Arsenic,  antimony,  and  bismuth  are  metals  that  are 
well  known  to  chemists,  but  not  of  great  interest  outside 
of  using  certain  of  their  compounds  employed  in  medi- 
cine and  the  arts. 

Arsenic  (As)  is  used  in  insecticides  such  as  Paris 
green.  Antimony  (Sb)  occurs  as  metal  in  alloys  with 
lead,  which  it  hardens.  Its  chief  salt  is  tartar  emetic,  or 
antimony  potassium  tartrate.  It  is  used  as  a  mordant 
in  dyeing.  Bismuth  is  used  in  medicine  as  subnitrate  of 
bismuth,  a  sedative.  As  a  metal  it  is  used  to  cause  lead 
alloys  to  melt  at  very  low  temperatures,  even  below  the 
boiling  point  of  water.  This  alloy  is  then  used  for 
automatic  fire  sprinklers,  which  are  actuated  by  the 
presence  of  the  water  after  the  fusible  alloy  has  melted. 


CHAPTER  X 

GOLD   AND   SILVER 

THE  so-called  noble  metals  are  silver,  gold,  and 
platinum.  The  chief  chemical  property  in  which  these 
metals  differ  is  their  solubility  in  acids.  Silver  is 
soluble  in  several  acids,  particularly  nitric.  Gold  and 
platinum  are  not  dissolved  by  any  one  acid,  and  it  is 
only  by  the  combined  action  of  nitric  and  hydrochloric 
acids  (called  aqua  regia)  that  they  can  be  dissolved. 
Platinum  (Pt)  is  used  to  make  crucibles  and  dishes  for 
the  laboratory,  as  it  withstands  nearly  all  reagents,  and 
temperatures  up  to  1760°  C.  (3200°  F.) .  It  is  21.5  times 
as  heavy  as  water.  It  is  very  costly,  about  $150.00  per 
ounce  being  paid  for  it  in  1914.  This  is  due  to  the 
limited  supply  and  its  recent  use  in  jewelry  and  in  elec- 
tric light  bulbs,  as  well  as  in  the  laboratory.  For  mak- 
ing jewelry  and  other  objects  out  of  platinum,  iridium 
up  to  10  per  cent,  is  alloyed  with  the  platinum  to  make 
it  stronger. 

Silver  (Ag)  has  been  a  highly  prized  metal  since  the 
earliest  antiquity.  It  has  been  just  rare  enough  to 
render  it  somewhat  costly,  yet  can  be  used  for  many 
purposes.  It  is,  like  gold,  largely  used  for  ornamental 
purposes,  and  its  comparative  scarcity  and  its  being 

133 


134  CHEMISTRY  OF  FAMILIAR  THINGS 

only  slightly  subject  to  corrosion  renders  it  a  desirable 
medium  of  exchange  and  sometimes  a  standard  of  value. 
Silver  is  produced  from  sulphide  ores  by  roasting  and 
smelting,  generally  in  the  presence  of  lead,  because  it  is 
found,  as  a  rule,  with  lead,  and  lead  protects  it  against 
loss.  It  is  precipitated  from  melted  lead  by  a  little  zinc, 
as  silver  is  more  soluble  in  molten  zinc  than  in  lead.  Zinc 
can  then  be  distilled  off  at  temperatures  which  leave  sil- 
ver behind.  Silver  is  malleable  and  ductile  but  harder 
and  less  easily  tarnished  than  lead.  Hydrogen  sulphide 
gas,  however,  readily  darkens  silver.  Even  the  sul- 
phur compounds  in  eggs  will  darken  silver  by  forming 
silver  sulphide  (Ag2S)  if  left  in  contact  with  the  metal 
very  long.  This  is  nearly  the  only  drawback  to  silver, 
although  some  people  object  to  handling  silver  dollars. 
Most  people  could  carry  their  week's  wage  in  silver, 
however,  as  a  dollar  weighs  about  an  ounce  avoirdupois. 

Silver  (fine)  Copper 

U.  S.  coin 900  parts  per  M.  100  parts  per  M. 

Table  silver 750-950  parts  per  M.  250-50  parts  per  M. 

Sterling 925  parts  per  M.  75  parts  per  M. 

Sheffield  plate  is  not,  as  some  people  think,  electro- 
plated on  base  metal,  but  is  (or  should  be,  to  be  genuine) 
composed  of  sheets  of  silver  and  copper  that  have  been 
rolled  together  at  a  temperature  a  little  below  the  melt- 
ing point  of  silver.  Silver  plating  is  an  art  that  has 
been  greatly  improved  of  late  by  the  introduction  of 
mechanical  appliances  that  rotate  the  articles  so  that 


GOLD  AND  SILVER  135 

they  are  coated  uniformly.  There  are  polishes  on  the 
market  that  really  do  plate  silver  on  places  where  brass 
or  base  metal  is  exposed,  as  well  as  clean.  This  is  ef- 
fected by  having  a  little  silver  in  the  preparation  in  a 
state  of  chemical  instability,  and  the  base  metal  of  the 
article,  such  as  copper  or  zinc  (in  brass),  tends  to  go 
into  solution  in  place  of  silver,  as  it  can  form  stronger 
compounds. 

To  clean  silver  where  no  coating  is  necessary,  the 
best  way  is  to  do  it  electrolytically.  There  is  now  on 
the  market  an  arrangement  which  consists  essentially 
of  a  zinc  tray  with  racks  to  hold  the  silver.  A  bath  is 
made  up  of  a  hot  solution  of  salt  and  bicarbonate  of 
soda.  When  the  more  or  less  tarnished  silver  is  im- 
mersed in  the  liquid  and  in  contact  with  zinc,  galvanic 
action  is  set  up.  The  zinc  is  electropositive  to  silver, 
forming  an  anode,  which  goes  into  solution  as  chloride. 
The  sodium  which  was  combined  with  the  chlorine  to 
form  salt  goes  to  the  cathode  or  the  silver.  It  acts  upon 
water  at  this  place,  releases  hydrogen,  and  forms  so- 
dium hydroxide.  The  hydrogen,  in  process  of  forma- 
tion, acts  upon  silver  sulphide  (the  tarnish)  and  re- 
forms silver,  while  the  sulphur  goes  into  the  solution. 
Of  course,  the  caustic  soda  formed  takes  some  carbon 
dioxide  from  a  little  of  the  bicarbonate,  forming  normal 
carbonate.  These  pans  offer  a  nice  little  lesson  in  elec- 


136  CHEMISTRY  OF  FAMILIAR  THINGS 

trochemistry  and  improve  the  appearance  of  the  silver 
without  much  labor. 

Silver  can  be  coated  on  practically  any  article,  even 
glass.  A  coating  of  silver  called  a  1 1  silver  mirror ' '  can 
be  produced  on  glass  by  the  use  of  unstable  silver  solu- 
tions.1 

As  silver  salts  are  the  chief  active  agents  in  making 
photographic  images,  we  must  say  something  about  the 
essentials  of  the  chemistry  of  photography.  The  dry 
plate  (in  contradistinction  to  the  earlier  wet  plate, 
which  could  be  used  only  by  professional  photogra- 
phers) is  coated  with  a  gelatin  emulsion  containing  a 
silver  halide,  such  as  silver  bromide  (AgBr),  in  a 
finely  divided,  freshly  precipitated  condition.  In  the 
case  of  films,  thin  strips  of  transparent  celluloid  are 

1  Silvering  on  Glass. — When  alkaline  solutions  of  silver  salts  are 
mixed  with  certain  organic  compounds  like  grape-sugar,  Rochelle  salt, 
etc.,  the  silver  is  deposited  on  the  surface  of  the  vessel  in  which  it  is 
contained  as  a  thin,  coherent  film.  The  following  process  will  yield 
satisfactory  results  if  the  glass  be  first  thoroughly  cleaned  with  alkali 
and  then  washed  with  distilled  water : 

Dissolve  7.8  grammes  of  silver  nitrate  in  60  c.c.  of  water  and 
divide  the  solution  in  two  equal  portions.  Dissolve  also  3.11  grammes 
of  Rochelle  salt  in  1180  c.c.  of  water  and  heat  the  solution  to  the  boil- 
ing point.  Add  to  it  gradually  (so  as  not  to  stop  the  ebullition)  one 
of  the  portions  of  silver  solution,  boil  some  10  minutes  longer,  cool,  and 
decant  the  clear  liquid.  To  the  other  half  of  the  silver  solution  add  just 
sufficient  ammonia  water  to  dissolve  the  precipitate  which  is  first 
formed,  or  only  leave  a  faint  cloudiness;  then  add  360  c.c.  of  water  and 
filter.  Equal  portions  of  these  two  solutions,  when  mixed  and  poured 
on  glass,  will  deposit  a  brilliant  coating  of  silver  in  about  10  minutes, 
according  to  the  temperature  of  the  room.  The  coating  of  silver  should 
then  be  well  washed,  dried,  and  varnished.  ( Sadtler  and  Coblentz. ) 


GOLD  AND  SILVER  137 

coated  with  gelatin.  The  high  lights  of  the  object  re- 
duce the  silver  bromide  more  or  less  completely  to  a 
compound  containing  less  bromine  ( Ag2Br) .  The  nega- 
tives still  look  milky  white,  due  to  silver  salt,  after 
exposure  in  the  camera. 

The  plates  are  next  put  in  the  developing  bath,  which 
is  composed  of  an  organic  substance  that  is  capable  of 
changing  this  acted-upon  bromide  to  metallic  silver 
which  is  black  and  opaque.  These  developers  are  known 
by  names  as  hydroquinon,  ikonogen,  metol,  etc.,  and  owe 

... 

their  efficiency  to  their  being  mild  reducing  agents. 
The  next  operation  is  to  put  the  negatives  into  a  solu- 
tion of  sodium  thiosulphate,  commonly  called  "hypo- 
sulphite of  soda, "  which  dissolves  out  all  the  unchanged 
silver  bromide.  The  lights  of  the  image  are  now  repre- 
sented by  dark  places  in  the  negative  and  shadows  by 
transparent  areas.  After  thorough  washing  and  dry- 
ing, the  negative  is  completed  and  the  positive  is  now 
to  be  made.  For  this  purpose  paper  that  is  coated  with 
a  similar  solution  to  that  on  the  plate,  only  less  sensi- 
tive to  light,  is  exposed  to  the  light  that  comes  through 
the  lighter  areas  which  correspond  to  dark  parts  in  the 
image.  This  makes  dark  places  on  the  positive.  The 
processes  employed  in  treating  the  positive  are  a  little 
different  from  those  of  the  negative.  The  first  solution 
is  a  ' 'toning"  solution  which  contains  gold  or  platinum 
salts.  The  silver  bromide  which  has  been  affected  by 


138  CHEMISTRY  OF  FAMILIAR  THINGS 

the  light  is  capable  of  reducing  gold  or  platinum  salts, 
the  metals  of  which  take  the  place  of  the  altered  silver 
bromide.  Then  by  the  use  of  "hypo"  again  the  paper 
is  cleared  of  unaltered  silver  salt.  In  making  this 
positive,  the  lights  and  shadows  are  reversed  again, 
which  therefore  makes  the  image  the  true  one,  as  it  was 
reversed  in  the  negative,  both  in  light  and  shadow  and 
in  the  location  of  objects. 

There  have  been  great  advances  in  the  chemistry  of 
photography  in  negative  developers  and  in  printing 
papers.  It  was  difficult  for  a  long  time  to  get  the  true 
color  value  of  red  lights,  which  showed  up  quite  dark 
with  ordinary  processes.  Now  it  is  possible  to  get  the 
true  value  by  having  red  colors  in  the  gelatin  emulsion 
or  silver  compounds  of  red  colors,  such  as  the  organic 
color  eosin.  This  process  is  called  orthochromatic  pho- 
tography. Thus  red  rays  are  somewhat  absorbed, 
which  makes  the  total  light  shown  about  normal.  Color 
photography  is  still  in  its  experimental  stages.  It  is 
possible  with  color  screens  to  make  three  negatives  so 
that  each  takes  certain  colors,  and  a  composite  litho- 
graphic print  or  lantern-slide  can  be  made  that  shows 
in  their  true  values  the  colors  of  the  original.  It  is  not 
yet  possible  to  print  directly  on  paper  in  colors  from 
an  exposed  plate. 

Gold  (Au)  occurs  native  or  "free"  in  quartz  or 
gravel.   It  occurs  combined  in  lead,  copper  ores,  and  as 


GOLD  AND  SILVER  139 

telluride  of  gold,  etc.  Gold  is  obtained  from  quartz  by 
crushing  in  stamp-mills  and  collecting  the  particles  by 
means  of  mercury,  which  has  a  strong  affinity  for  free 
gold,  and  the  mercury  is  easily  separated  from  the  wet, 
crushed  ore  because  of  its  weight  and  fluid  condition.  In 
so-called  "  placer "  mining  streams  of  water  from  high- 
pressure  pipe  lines  rip  out  the  sand  and  earth,  tearing 
down  whole  hills.  The  gold  is  so  much  heavier  than  the 
gravel  that  it  does  not  go  so  far  in  the  water-course 
that  results,  and  is  caught  in  sluices  as  practically  pure 
gold  or  "gold  dust."  Besides  these  ways  of  obtaining 
the  gold,  the  cyanide  method  is  the  most  important,  and 
after  that  the  chlorine  method  or  chloridizing.  These 
are  chemical  methods  and  the  preceding  are  physical, 
as  solution  in  mercury  does  not  effect  a  chemical  change 
in  the  gold  any  more  than  salt  is  changed  when  it  dis- 
solves in  water.  Gold  is  thrown  out  of  solution  from 
cyanide  of  potassium  or  chlorine  water 'by  means  of 
zinc  strips  or  by  electricity. 

Gold  coins  are  90  per  cent,  gold  and  10  per  cent, 
copper,  as  pure  gold  is  too  soft  for  practical  use  and 
copper  hardens  it.  This  alloy  would  be,  by  the  well- 
known  jewellers  *  scale,  21.6  carats.  Similarly,  18-carat 
would  be  75  per  cent,  gold,  and  14-carat  gold  is  only  58 
per  cent.  pure.  Gold  is  one  of  the  heaviest  metals,  being 
about  19.5  times  as  heavy  as  water,  mercury  being  13.5. 
It  is  one  of  the  toughest  and  most  malleable  of  metals. 


140  CHEMISTRY  OF  FAMILIAR  THINGS 

It  can  be  beaten  out  into  sheets  of  almost  imperceptible 
thinness.  These  Sheets  of  gold  leaf  can  be  made  so 
thin  that  they  will  transmit  green  rays  of  light.  A  form 
of  colloidal  gold 2  with  tin  is  made  by  precipitating  gold 
chloride  solution  with  a  solution  of  stannous  chloride 
(SnCl2).  Other  colloidal  gold  solutions  are  made  by 
the  use  of  ferrous  sulphate  (FeSOJ  and  oxalic  acid. 
A  red  colloidal  solution  is  obtained  by  adding  a  little 
silicate  of  soda  and  formaldehyde  to  gold  chloride.  This 
color,  purple  of  Cassius,  is  used  to  paint  porcelain  to 
produce  gold  bands  and  decoration. 

The  story  of  radium  is  a  very  weird  one  and  it 
could  easily  lead  us  into  chemical  theory  too  involved 
for  this  book.  It  may  be  told  in  outline,  however,  as  it 
has  great  bearing  on  chemistry,  physics,  and  cos- 
mogony. 

In  1896  Becquerel,  a  French  chemist,  discovered  ra- 
diations emanating  from  a  mineral  called  pitch-blende, 
which  influenced  the  photographic  plate  and  made  phos- 
phorescent substances  luminous  in  the  dark.  These 
were  then  merely  called  Becquerel  rays.  In  1898,  how- 
ever, Madame  Curie  and  her  husband,  Professor  Curie, 
discovered  what  afterwards  was  called  radium  in  pitch- 
blende residues.  One  ton  of  pitch-blende  yielded  ten 
milligrammes  of  radium.  The  pure  radium  bromide  was 

aFine  suspension  in  water  that  does  not  settle  out  and  particles 
too  small  to  be  seen,  even  with  a  microscope. 


PLATE  XIII. 


Photo  by  the  Author. 
Tray  for  electrolytic  silver  cleaning.      Alternate  pieces  of  silver  have  been  cleaned. 


A 


Photo  by  Williams,  Brown  &  Earle. 

Photograph  made  with  radium,  showing  degrees  of   opacity   of    different   thicknesses   of 
lead  glass.     Crosses  are  lead. 


GOLD  AND  SILVER  141 

prepared,  and  radium  was  found  to  have  a  high  molecu- 
lar weight  of  226.4,  one  of  the  highest  molecular  weights 
that  is  known. 

Eadium  continuously  emits  enormous  quantities  of 
heat  because  of  a  molecular  degradation  that  is  in  prog- 
ress and  the  bombardment  of  matter  with  the  rapidly 
vibrating  negative  electricity  emitted.  It  is  estimated 
that  all  the  radium  existing  will  have  gone  over  into 
other  substances,  such  as  helium  and  what  scientists 
call  negative  electricity,  in  about  ten  thousand  years. 

Eadium  is  always  found  associated  with  the  metals 
of  higher  molecular  weight,  such  as  urmium,  and  there 
is  good  reason  to  believe  it  has  been  produced  from 
uranium  by  dissociation  of  the  latter,  just  as  radium 
itself  dissociates,  only  it  is  supposed  that  the  radium 
now  in  existence  has  taken  about  ten  million  years  to 
form.  In  the  descent  of  radium  it  goes  through  several 
stages,  giving  off  helium  gas  and  a  rays  with  very  great 
differences  in  the  rate  of  decomposition.  Eadium  has 
very  marked  activity,  which  is  particularly  character- 
istic of  the  substance.  It  makes  air  a  good  conductor 
of  electricity,  due  to  the  emanation  of  conductive  gas. 
Thus  it  draws  the  electric  charge  from  a  gold-leaf  elec- 
troscope. Eadium  induces  phosphorescence  and  chemi- 
cal change.  Sir  William  Eamsay  has  stated  that  he 
has  obtained  lithium  from  copper  by  the  influence  of 
radium  emanation,  but  Madame  Curie  and  others  have 


142  CHEMISTRY  OF  FAMILIAR  THINGS 

questioned  this  finding.  The  subject  is  a  difficult  one, 
and  all  honor  should  be  given  to  the  opinion  of  so  consci- 
entious and  versatile  a  scientist  as  Kamsay,  particu- 
larly as  a  stable,  low-atomic-weight  element  like  copper 
(63.5)  could  hardly  be  expected  to  dissociate  as  easily 
as  the  high-atomic-weight  elements,  such  as  uranium 
(238.5),  thorium  (232.4),  and  radium  (226.4),  and 
very  little  decomposition  product  might  be  expected  at 
best. 

Thorium  goes  through  a  series  of  degradations 
much  like  radium.  The  products  of  these  transforma- 
tions, for  lack  of  better  terms,  are  given  Greek  letters, 
such  as  a,  /?,  and  y  rays.  One  of  the  greatest  shocks 
radium  has  given  science  is  the  thought  that  the  law 
of  the  conservation  of  energy  may  be  violated.  This 
is  not  in  the  least  true,  although  the  radio-active  ele- 
ments have  shown  us  that  the  energy  of  atomic  integrity 
far  surpasses  any  force  of  union  or  cohesion  of  which 
we  have  knowledge. 


CHAPTER  XI 

THE  CHEMISTRY  OF  THE  EARTH 's  EVOLUTION 

To  CONSIDER  properly  from  a  chemical  stand-point 
the  changes  which  the  matter  of  our  globe  has  under- 
gone, we  will  have  to  give  some  thought  to  the  earliest 
condition  of  things  of  which  we  have  any  evidence. 
Laplace,  at  the  beginning  of  the  last  century,  by  study- 
ing the  movements  of  planets  noticed  how  they  seemed 
to  move  in  planes  relative  to  each  other.  This  motion, 
taken  in  conjunction  with  the  phenomenon  of  the  rings 
of  Saturn  and  the  movement  of  asteroids,  led  him  to 
the  belief  that  the  solar  system  had  been  at  one  time  a 
rotating  mass  of  hot  gases.  This  gaseous  matter  in 
time  condensed  to  a  liquid  state  and  finally  separated 
into  spherical  globules,  with  the  sun  in  the  centre  of 
rotation  and  the  other  globules  revolving  about  in  the 
same  plane  as  the  original  nebula.  This  hypothesis 
is  generally  credited  among  scientists. 

To  look  at  this  subject  in  the  most  elementary  way, 
we  must  consider  practically  the  elements  we  know 
(with  possibly  some  we  have  not  yet  discovered)  in  a 
liquid  or  gaseous  condition,  forming  a  revolving  sphere. 
Naturally  these  elements,  more  or  less  in  fused  solution, 
together  formed  the  earth  at  this  stage,  while  the  uncon- 

143 


144  CHEMISTRY  OF  FAMILIAR  THINGS 

densed  gases  formed  an  envelope  surrounding  the 
central  mass.  When  the  globe  was  very  hot  at  the 
surface,  say  1000°  C.  (1832°  F.),  many  elements  nor- 
mally solid  would  have  been  in  the  atmosphere  around 
the  earth,  just  as  there  are  a  large  number  of  elements, 
such  as  iron,  zinc,  aluminum,  etc.,  in  the  sun's  atmos- 
phere. The  molten  mass  which  by  evolution  has  formed 
our  planet  contained  the  rock-forming  elements, — the 
silica,  aluminum,  iron,  calcium,  magnesium,  sodium,  po- 
tassium, etc.,  while  the  envelope  probably  contained 
oxygen,  nitrogen,  carbon  dioxide,  steam,  zinc,  etc.  The 
earth  was  different  in  composition  from  what  it  now  is, 
and  the  primitive  atmosphere  was  certainly  very  dif- 
ferent then  from  what  it  is  at  present,  or  any  time  since 
life  has  been  on  the  earth.  There  are  reasons  for  believ- 
ing that  it  was  at  one  time  too  rich  in  carbon  dioxide  to 
support  life,  and  until  the  earth  was  cool  enough  there 
was  no  condensed  water  on  the  surface,  although  steam 
may  have  permeated  the  molten  rock  to  some  extent,  as 
gases  are  absorbed  by  molten  metal  under  certain  con- 
ditions. 

Geologists  have  made  a  careful  study  of  the  surface 
rocks,  and  find  that  the  original  rocks  which  come  to 
the  surface  in  many  places  are  of  generally  the  same  ap- 
proximate composition.  How  far  down  from  the  sur- 
face this  general  uniformity  exists  cannot  be  stated. 
Some  think  the  heaviest  metals  are  at  the  centre,  as 


THE  CHEMISTRY  OF  THE  EARTH'S  EVOLUTION        145 

the  specific  gravity  of  the  entire  earth  is  greater  than 
the  surface  rocks,  and  that  probably  iron  constitutes 
most  of  the  mass  at  the  centre.  This  idea  has  been  en- 
tertained partly  because  meteorites  generally  consist  of 
iron  or  iron  and  nickel.  Others  believe  that  the  com- 
position is  essentially  the  same  as  at  the  surface  and 
that  the  increase  in  density  is  due  to  pressure.  It  would 
seem  probable  to  the  writer  that,  as  the  earth  was  first 
formed  by  the  most  readily  condensable  elements,  such 
as  aluminum,  silicon,  calcium,  and  iron,  they  formed  a 
homogeneous  mass  which,  from  the  movements  due  to 
rotation,  would  be  more  or  less  mixed  and  made  uni- 
form in  composition.  Oxygen,1  as  the  temperature  was 
lowered,  reacted  with  the  elements  at  the  surface,  and 
their  interaction  formed  a  crust  composed  of  molten 
silicates,  etc.,  which  now  compose  the  rocks. 

Judging  from  the  movements  of  the  earth's  surface 
and  volcanic  activities,  it  is  thought  that  the  solid  crust 
is  not  very  thick,  say,  about  10  miles.  Below  this  there 
is  molten  rock  and  possibly  below  this  the  same  elements 
in  a  melted  state  without  oxygen,2  i.e.,  in  a  free  state. 
The  igneous  rocks  are  essentially  like  the  very  hard, 

1 202    +     Si2    =  2Si02 
oxygen       silicon       silica 

302    +       2A12      =   2A1203 
oxygen      aluminum      alumina 
A1203    +  2SiO2  =  Al2Si207 

alumina      silica       aluminum  silicate,  or  anhydrous  clay 
2  This  last  hypothesis  is  purely  a  surmise  of  the  writer. 

10 


146  CHEMISTRY  OF  FAMILIAR  THINGS 

durable  and  widely  distributed  rock  known  as  granite. 
The  average  composition,  according  to  Clark,3  of  this 
mass  is  about  as  follows : 

Feldspar  (silicates  of  alkalies,  alkali  earths, 

and  alumina)  59.5  per  cent. 

Hornblendes  (magnesia,  lime,  iron  silicate)  .16.8  per  cent. 

Quartz  (silica)    12.0  per  cent. 

Biotite  (mica),  magnesia,  alumina  and  potas- 
sium silicate  3.8  per  cent. 

Titanium  minerals  1.5  per  cent. 

Apatite   (lime  phosphate)    6  per  cent. 

Less  abundant  minerals,  including  the  useful 

metals,  such  as  zinc,  lead,  etc 5.8  per  cent. 


100.0  per  cent. 

This  somewhat  complex  rock  contains  all  there  was 
on  the  surface  at  a  time  before  life  began  on  the  earth. 
From  this  substance  have  developed,  by  a  process  of 
evolution,  with  the  help  of  the  atmosphere  and  the  heat 
of  the  sun,  the  varied  inorganic  materials  that  make 
up  the  surface  of  the  earth.  With  life  in  addition  all 
the  organic  substances  were  made.  . 

In  the  main  there  have  been  two  classes  of  combined 
chemical  and  physical  actions  on  the  earth: 

A.  Tearing-down  processes. 

B.  Building-up  processes. 

The  tearing-down  processes  began  when  water 
started  its  cycle  of  precipitation,  flowing  off  the  land 
into  the  sea,  evaporation  and  passage  back  to  the  land, 
and  the  work  has  been  kept  up  incessantly.  The  build- 

8  The  Data  of  Geological  Chemistry,  F,  W.  Clark,  U.  S.  Geol.  Survey, 
1908.  ;  > 


THE  CHEMISTRY  OF  THE  EARTH'S  EVOLUTION       147 

ing-up  processes  began  when  the  disrupted  substances 
began  to  be  accumulated  in  new  locations  on  the  floor 
of  the  ocean.  As  the  tearing-down  processes  are  going 
on  now,  we  can  form  some  idea  as  to  what  has  been  in 
progress  through  the  ages.  The  only  probable  differ- 
ence is  that  the  rate  of  change  has  varied.  Some  of 
the  tearing-down  agencies  that  acted  upon  the  orig- 
inal granite  or  igneous  rock,  upon  rocks  formed  from 
it,  and  upon  rocks  formed  from  these  rocks  may  be 
referred  to:  (a)  Eain  and  flowing  water;  (fc)  wave 
motions  at  the  sea-shores;  (c)  glacial  streams;  (d) 
expansion  due  to  freezing  in  crevasses;  (e)  wind-blown 
sand;  (/)  vegetation;  (#) changes  in  temperature;  (h) 
animals ;  (i)  acids,  such  as  nitric,  formed  from  lightning 
discharges,  and  carbon  dioxide. 

Most  of  these  agencies  are  purely  mechanical  and 
their  actions  are  obvious,  and  only  those  changes  of  a 
more  or  less  chemical  nature  will  be  discussed  here. 
Mechanical  attacks  often  precede  the  chemical,  how- 
ever, and  prepare  the  way  for  the  latter,  particularly 
with  the  granite,  which  does  not  wear  away  very  fast 
until  pieces  split  off  and  come  in  contact  with  the  soil. 
The  rain  is  a  mechanical  process,  but  carbon  dioxide, 
oxygen,  and  oxides  of  nitrogen  are  always  ready  for 
joint  chemical  action.  The  acids  attack  the  complex 
silicates,  and  water  frequently  combines  to  form  new 
hydrated  minerals.  These  hydrated  minerals  are  apt 


148  CHEMISTRY  OF  FAMILIAR  THINGS 

to  be  more  bulky  than  the  original  minerals  and  help  to 
disrupt  the  rocks  as  driven  wedges  would  a  tree  trunk. 
Vegetation  has  been  an  important  factor  in  rock  de- 
composition after  the  start  was  made.  Lichens  collect 
soil  on  the  rocks  and  vegetation  springs  up  and  the 
roots  widen  clefts  in  the  rocks.  Acids  are  formed  on 
the  decay  of  the  plants  as  the  seasons  change. 

In  arid  regions  the  rocks  do  not  decompose  very 
quickly,  but  loess  and  adobe  are  formed  mechanically 
by  wind-borne  particles.  In  the  Hawaiian  Islands  it  is 
quite  noticeable  that  the  rocks  on  the  mountains  are 
quite  eroded  and  worn  on  the  side  towards  the  prevail- 
ing moist  winds  and  are  angular  on  the  sides  away  from 
the  rains.  In  desert  places  in  Southwestern  United 
States  the  rocks  are  worn  away  by  sand  blasts  and  by 
the  unequal  expansion  and  contraction  due  to  the  great 
changes  in  temperature  between  day  and  night.  These 
desert  sands  appear  to  be  barren  when  dry,  but  as 
soon  as  this  soil,  composed  of  mechanically  disin- 
tegrated rocks,  becomes  moist  from  irrigation,  it  is 
enormously  productive.  The  reason  is  the  mineral  plant 
foods,  such  as  phosphates  and  potassium  carbonate,  are 
not  washed  away  in  rivulets  and  streams.  This  soil  is 
alkaline,  and  it  is  hard  to  see  why  nearly  all  soil  is  not 
alkaline  because  of  the  alkalies  released  from  the  feld- 
spar. One  acid  strong  enough  to  neutralize  these  alka- 
lies is  sulphuric  acid,  formed  from  the  weathering  of 


THE  CHEMISTRY  OP  THE  EARTH'S  EVOLUTION      149 

sulphide  of  iron  (iron  pyrites).  By  its  action  on  cal- 
cium compounds  there  is  formed  calcium  sulphate  (the 
chief  constituent  of  most  so-called  permanently  hard 
waters),  and  with  weak  sodium  compounds  it  forms 
sodium  sulphate. 

It  is  a  matter  of  great  scientific  interest  as  to  whence 
the  sodium  chloride  (salt)  of  the  ocean  was  derived,  as 
the  mineral  matter  of  the  streams  differs  greatly  from 
that  of  the  ocean.  The  chief  compounds  of  sodium  (in 
the  order  of  magnitude)  are,  in  the  ocean,  chlorides,  sul- 
phates, and  carbonates,  while  in  average  river  water 
the  order  is  carbonates,  sulphates,  and  chlorides.  Fur- 
thermore, sodium  salts  predominate  very  greatly  in  the 
ocean,  while  potassium  salts  are  well  up  to  sodium 
in  quantity  in  river  waters.  Why  are  the  lime  and  mag- 
nesia salts  greater  in  river  waters  than  the  sodium  and 
less  in  the  ocean!  Some  explanation  of  these  enigmas 
may  be  forthcoming,  but  we  cannot  adequately  explain 
all  the  points  of  apparent  discrepancy  that  may  be 
brought  forth.  When  elements  first  began  to  unite 
with  those  for  which  they  had  the  strongest  affinities, 
sodium  (one  of  the  strongest  base-forming  elements) 
united  largely  with  chlorine  (one  of  the  strongest,  if 
not  the  strongest,  acid-forming  element),  and  in  all 
the  changes  that  have  subsequently  taken  place,  where 
land  has  risen  from  the  sea  or  continents  have  been 
in  whole  or  in  part  submerged,  the  chlorine  and  sodium 


150  CHEMISTRY  OF  FAMILIAR  THINGS 

have  remained  combined.  Now  many  of  the  otliei 
ments  are  carried  into  the  ocean  in  great  quantities  in 
the  aggregate,  but  are  weeded  out,  as  it  were,  by  animal 
life.  Silica  has  been  removed  by  diatoms ;  lime  by  co  ^1, 
shell-fish,  crustaceans,  etc. ;  potassium  by  kelp  and  c 
marine  plants  and  the  dead  plants  buried  in  loa  r 
ooze  in  the  sea  floor.  Even  sulphates  are  supposed  be 
changed  by  some  minute  organisms,  with  absor  ion 
of  sulphur.  One  reason  why  geologists  have  been  >n- 
cerned  with  the  salt  of  the  sea  is  because  they  thcu  lit 
they  could  calculate  from  its  quantity  the  age  of 
world,  by  measuring  the  sodium  that  was  at  presenl 
tering  from  rivers  and  assuming  that  the  total  amc 
came  there  by  the  slow  process  of  supply  from  th  se 
sources. 

We  have  spoken  of  the  tearing-down  processes  of  the 
elements.  These  may  have  been  much  more  rapid  at  one 
time  when  the  heat  was  greater  and  there  was  more 
carbon  dioxide  in  the  air.  Possibly  nitric  acid  from 
frequent  thunder-storms,  due  to  the  masses  of  clouds 
that  were  undoubtedly  making  f  rictional  electricity  by 
their  motion  and  discharging  the  same  frequently,  was 
also  in  great  supply.  Besides  the  tearing-down  and  the 
up-building  processes,  there  have  been  the  volcanic 
manifestations  which  partake  of  both  categories.  Very 
interesting  formations  of  volcanic  material  are  seen  in 
places  where  regular  fracture  has  given  it  a  columnar 


PLATE  XVI. 


Photo  by  Williams,  Brown  &  Earle. 

Characteristic  columnar  structure  in  lava  due  to  stresses  formed  in  cooling. 


THE  CHEMISTRY  OF  THE  EARTH'S  EVOLUTION      151 

structure,  as  in  the  Giant's  Causeway  and  elsewhere. 
Volcanic  eruptions  may  have  been  very  important  ele- 
ments in  world  transformation,  but  little  is  known  of 
their  real  cause  and  what  they  have  done,  although  they 
have  undoubtedly  been  potent  factors.  There  is  on 
the  sea  floor  beyond  the  reach  of  continental  deposits 
from  the  rivers  a  large  amount  of  red  clay  that  is 
thought  by  geologists  to  have  come  from  volcanic 
action.  This  material  is  richer  in  iron  than  clays  we 
find  on  land,  and  it  does  not  seem  to  have  come  from 
surface  rocks. 

The  building-up  processes  are  the  proper  study  of 
geologists,  but  there  is  a  great  deal  of  chemistry  to  be 
considered  as  well.  In  the  first  place,  the  material  worn 
away  by  streams  has  been  sorted  and  collected  through 
long  ages  in  somewhat  uniform  beds.  Coarse  sands 
were  carried  relatively  short  distances,  coarse  clays 
with  sand  farther,  and  the  finest  clays  greater  dis- 
tances, and  then  deposited.  The  soluble  salts,  such  as 
lime,  were  fully  diffused  only  to  be  collected  by  the 
coral  insect  and  other  means  and  united  into  great 
masses  and  raised  to  the  surface  by  insect  growth,  or 
by  the  slow  rising  of  that  part  of  the  earth's  crust. 

Geology  teaches  that  in  places  the  crust  was  lifted 
and  allowed  to  fall  a  number  of  times  in  succession,  so 
that  the  same  place  was  sea  bottom  or  elevated  land  at 
several  different  times,  as  shown  by  the  fossil  remains 


152  CHEMISTRY  OF  FAMILIAR  THINGS 

of  land  or  sea  organisms.  The  only  way  we  could  have 
obtained  a  stratified  secondary  rock  was  by  the  slow  ac- 
cumulations of  silt,  etc.,  under  water,  and  then,  after  it 
had  become  compacted  by  heat,  pressure,  and  liquid  and 
gaseous  binding  agents,  it  was  lifted  by  sub-surface 
forces.  In  this  way  clay  was  compacted  to  form  shale 
or  slate.  Carbonate  of  lime,  formed  by  precipitation 
from  the  bicarbonate  solution  and  from  insects,  was  by 
pressure  compacted  into  chalk  deposits,  and,  where  the 
pressure  was  great  enough,  dense  and  even  crystalline 
limestone  was  formed.  Sandstone  is  made  up  of  grains 
of  sand,  generally  cemented  together  by  silica  that  was 
not  crystalline  or  was  in  solution  or  colloidal  suspen- 
sion. Sometimes  it  was  cemented  by  means  of  car- 
bonate of  lime,  which  acted  as  a  binder  under  heat  and 
pressure.  The  various  secondary  rocks  are  too  numer- 
ous to  deal  with  here,  but  they  are  very  interesting. 
Some  of  them  are  nearly  as  hard  as  the  original  granite, 
because  of  being  subjected  to  heat  from  below  and  the 
pressure  of  perhaps  tens  of  thousands  of  feet  of  more 
recent  mineral  deposits.  Frequently  chemical  analy- 
sis will  not  show  the  difference  between  two  rocks,  one 
of  which  is  worthless  for  building  and  the  other  valu- 
able, as  the  difference  is  all  in  the  compactness.  The 
spaces  between  crystals  or  cleavage  planes  allow  of 
moisture  entering,  which,  when  it  freezes  in  winter,  dis- 
rupts the  rocks.  When  building  my  house  near  Phila- 


THE  CHEMISTRY  OF  THE  EARTH'S  EVOLUTION       153 

delphia,  a  few  years  ago,  there  were  fragments  of  rock 
that  seemed  quite  hard,  dug  out  near  the  surface  of  the 
ground,  and  pieces  lay  around  all  winter.  In  the  spring 
I  noticed  in  many  cases  these  had  crumbled  ready  to 
fall  to  pieces.  The  stone  below  this  layer  was  a  very 
hard  and  durable  quartzite  which  seemed  to  have  been 
made  by  the  compacting  of  a  gelatinous  silica,  and  this 
was  used  in  the  foundations.  With  further  reference  to 
personal  observations  in  this  vicinity,  I  have  noticed 
mica  schist  that  was  removed  in  grading  roads  and 
put  aside  for  building  purposes  and  after  a  few  winters 
a  large  pile  of  it  had  almost  completely  disintegrated. 
The  binder  was  weak  in  this  stone,  as  it  had  not  had 
enough  pressure,  or  had  been  well  on  the  road  to  slow 
decay  when  quarried.  Other  nearby  stone  of  similar 
appearance  has  had  a  good  reputation  for  durability, 
extending  over  a  hundred  years.  Most  people  have  to 
use  geologically  made-over  stone  for  building,  as 
granite  is  unsuitable  for  ordinary  house  use,  but  one 
should  study  the  stone  and  learn  its  established  repu- 
tation before  using  it. 

In  various  places,  notably  in  Florida  and  Tennessee, 
there  are  large  deposits  of  phosphate  of  lime  which 
seem  to  have  come  from  the  bones  of  fishes  and  the 
shells  of  crustaceans.  One  of  the  most  useful  of  the  de- 
posits formed  by  evaporation  of  prehistoric  inland 
seas  is  salt,  which  occurs  at  depths  (where  I  have  ob- 


154  CHEMISTRY  OF  FAMILIAR  THINGS 

served  the  location  of  the  strata)  of  about  two  thousand 
feet.  It  is  brought  to  the  surface  by  letting  in  water 
and  afterward  pumping  it  out  with  the  salt  in  solution. 
Sulphur  is  mined  in  a  somewhat  similar  way  in  Louisi- 
ana by  the  use  of  steam  under  pressure. 

Suppose  nature  had  not  made  over  the  rocks  and 
materials  as  she  has  and  sorted  and  concentrated  the 
elements !  We  would,  in  that  case,  probably  be  leading 
very  primitive  lives  at  this  time.  The  original  rocks 
contained  nearly  all  the  elements  we  have,  but  not  in 
the  convenient  forms  or  concentrated  condition  we  now 
find  them.  Then  aluminum,  lead,  copper,  zinc,  silver, 
gold,  and  all  the  metals  were  there  in  small  quantities. 
It  would  be  very  hard  or  impossible  to  smelt  granite  to 
obtain  iron  or  aluminum,  or  to  obtain  lime  from  it  in 
some  way.  We  never  would  have  found  the  traces  of 
silver  and  gold.  But  as  the  Archaean  rock  was  worn 
away,  these  valuable  metals  and  other  elements  were 
sorted  by  solution  in  solvent  waters  and  precipitated 
and  are  now  easily  available  for  our  use.  So  far  we 
have  dealt  with  the  inanimate  creation.  At  a  reasonably 
early  period  in  geological  history,  first  plant  life  and 
then  animal  life  entered  into  the  inheritance,  and  both 
of  these  forms,  by  their  remains,  have  given  valuable 
deposits  that  have  formed  strata  with  the  purely  in- 
organic rocks.  Most  people  know  that  peat  can  be  used 
as  a  fuel.  Peat  is  humus  from  decaying  vegetation. 


THE  CHEMISTRY  OF  THE  EARTH'S  EVOLUTION        155 

In  one  of  the  early  geological  periods,  called  the  Car- 
boniferous Age,4  vegetation  grew  very  rapidly,  due  to 
the  heat,  the  moisture,  and  the  carbon  dioxide  in  the 
air.  The  dead  plants  were  turned  to  a  kind  of  peat,  and 
then,  with  pressure,  as  the  clay,  etc.,  formed  above  it 
and  with  heat  from  below  the  solid  crust,  changes  took 
place  that  carbonized  the  material  further,  and  coal  was 
formed.  In  morasses,  perhaps,  oil  was  formed  from 
vegetable  remains  of  smaller  growth. 

We  note  stages  of  these  processes  at  the  present 
time, — the  formation  of  peat  as  already  referred  to, 
and  we  can  now  see  oil  formed  in  ponds  in  which  organic 
matter  is  decomposing  under  water.  Most  of  us  have 

4 Periods  of  Geologic  Time: 

Archaean  or  Eozoic 

f  Cambrian 

\  Silurian 
Paleozoic  or   Primary    /  Devonian 

I  Carboniferous 

(.  Permian 

C  Triassic 

Mesozoic  or  Secondary    .  .  J  Jurassic 

]  Lower  Cretaceous 
(^  Upper  Cretaceous 

C  Eocene 

Cainozoic  or  Tertiary J  Olig°<*ne 

J  Miocene 

/  Pliocene 

Quartenary  or  Post-tertiary  .          .  /  Pleistocene  or  Glacial 

I  Post-glacial  or  Human 


156  CHEMISTRY  OF  FAMILIAR  THINGS 

seen  gas  bubbles  come  to  the  surface  in  stagnant  pools 
and  an  oil  drop  spread  over  the  surface  of  the  water 
with  a  play  of  iridescent  colors.  The  writer's  father, 
Dr.  Samuel  P.  Sadtler,  was  about  the  first  to  show  that 
petroleum  could  be  obtained  from  vegetable  sources. 
He  distilled  vegetable  oils  under  pressure  and  obtained 
light  and  heavy  petroleum  oils.  Before  this  it  was 
thought  that  it  was  derived  only  from  animal,  if  from 
any  organic,  sources.  The  difference  between  these 
present-day  causes  and  effects  and  those  of  the  Car- 
boniferous Era  is  that  of  degree  but  not  of  kind. 

Great  quantities  of  woody  matter  were  decom- 
posed under  the  most  favorable  conditions  in  the  mak- 
ing of  coal.  Whole  tree  trunks  are  found  fully  converted 
into  coal  in  the  veins  as  they  are  worked.  Analogous 
agencies  probably  produced  oil  and  its  closely  allied  sub- 
stance, asphalt.  These  matters  are  only  subjects  of 
conjecture,  as  petroleum  oils  could  conceivably  have 
been  derived  from  the  action  of  water  on  metallic  car- 
bide&  In  any  case,  heat  and  pressure  have  had  de- 
cided influence,  and  much  of  the  petroleum  found  shows 
evidences  of  having  been  distilled  and  subsequently 
caught  and  condensed  to  liquid  again  in  strata  and 
localities  other  than  those  in  which  it  was  formed. 

Analyses  of  different  products  from  the  altera- 
tion of  organic  matter  by  bacterial  decomposition,  more 
or  less  out  of  access  of  air,  are  shown  herewith,  in 


THE  CHEMISTRY  OF  THE  EARTH'S  EVOLUTION       157 

the  order  beginning  with  wood  and  going  to  the  altera- 
tion products  that  seem  to  have  had  the  most  heat  and 
pressure.  Dr.  F.  Bergins  has  made  something  like  an- 
thracite coal  by  the  application  of  heat  and  pressure  to 
cellulose,  the  fibrous  substance  of  wood. 


Carbon  Hydrogen 

Wood  ......................   49.31  6.29.  44.40 

Peat  ............  .  ..........   59.71  5.27  32.07 

Lignite    ....................   69.82  5.90  24.28 

Bituminous  coal    ............   85.73  5.49  8.78 

Anthracite  coal   .............   93.90  3.22  2.88 

It  is  impossible  for  the  writer  to  recall  greater 
achievements  in  scientific  research  than  the  discov- 
eries of  the  great  geologists,  such  as  Descartes,  La- 
marck, Cuvier,  Lyell,  Werner,  Smith,  Agassiz,  and 
many  others,  both  of  the  older  and  the  more  recent 
investigators. 


CHAPTER  XII 

SOIL   AND   ITS    CONSERVATION 

JOHN  BURROUGHS,  in  "Time  and  Change,"  has  said 
many  things  like  the  following  so  beautifully  that  the 
writer  is  tempted  to  quote  a  sentence  or  two  to  intro- 
duce the  present  subject :  l '  What  an  astonishing  revela- 
tion, for  instance,  that  the  soil  was  born  of  the  rocks, 
and  is  still  born  of  the  rocks ;  that  every  particle  of  it 
was  once  locked  up  in  the  primitive  granite  and  was  un- 
locked by  the  slow  action  of  the  rain  and  the  dews  and 
the  snows ;  that  the  rocky  ribs  of  the  earth  were  clothed 
with  this  fertile  soil,  out  of  which  we  came  and  to  which 
we  return  by  our  own  decay;  that  the  pulling  down  of 
the  inorganic  meant  the  building-up  of  the  organic ;  that 
the  death  of  the  crystal  meant  the  birth  of  the  cell,  and 
indirectly  of  you  and  me  and  of  all  that  lives  upon  the 
earth. " 

The  tillage  of  the  soil  and  the  nurture  of  plants  is 
of  great  interest  aside  from  its  economic  importance, 
and  there  are  but  few  who  do  not  take  some  interest  in 
garden  or  farm  work  if  they  have  had  an  opportunity 
to  study  its  processes.  That  chemistry  has  had  a  pre- 
dominant part  in  placing  agriculture  on  an  exact  basis 
is  well  known,  and  all  successful  farmers  and  truck 
raisers  make  use  of  chemistry. 
158 


SOIL  AND  ITS  CONSERVATION  159 

Soil  is  made  up  of  weathered  or  decayed  rock  and 
organic  matter.  Soil  may  come  from  the  weathering 
of  local  rocks  or  it  may  be  carried  by  glacial  action 
from  distant  points  or  by  streams  from  higher  levels. 
In  the  first  instance  the  soil  is  known  as  sedimentary, 
and,  in  the  second,  alluvial  or  transported  soil.  Prac- 
tically all  rocks  weather,  especially  while  in  their  native 
locations.  Some  rocks,  such  as  granite,  when  dressed 
and  placed  in  buildings,  do  not  seem  to  weather  to  any 
appreciable  extent,  but  they  are  not  subjected  to  all 
the  influences  of  surface  outcroppings  as  in  natural  sit- 
uations. All  rocks  have  more  or  less  spaces  between 
particles  or  portions  of  the  rock.  If  large,  they  are 
cracks  or  fissures,  and  if  very  small,  they  may  be  only 
the  spaces  between  individual  crystals.  The  main  in- 
fluences of  soil  formation  are: 

A.  The  freezing  and  thawing  of  water  in  the  inter- 
stices of  rock. 

B.  The  action  of  carbon  dioxide  and  water  on  lime- 
stone *  and  feldspar.2 

C.  The  similar  action  of  humic  acid  on  limestone 
and  feldspar. 

1  The  carbon  dioxide  unites  with  the  limestone  or  calcium  carbonate 
to  form  dicarbonate,  which  is  soluble  in  water.    Thus,  CaCOs  +  CO2  + 
H2O  =  CaH2(CO3)2. 

2  Feldspar  is  a  silicate  of  sodium  or  potassium  and  aluminum.    The 
water  assisted  by  the  carbon  dioxide  dissolves  out  the  sodium  or  potas- 
sium and  leaves  aluminum  silicate  or  clay,  thus  2KAlSi3O8  +  2HaO  -f- 
C02  =  H4Al2Si2O9  +  4Si02  -f  K2C03,  as  a  powder  in  place  of  the  dense 
crystalline  mineral. 


160  CHEMISTRY  OF  FAMILIAR  THINGS 

D.  The  disintegration  of  rocks  by  means  of  the  roots 
of  plants. 

E.  Splitting  by  alternate  expansion  and  contraction 
due  to  heat  and  cold. 

F.  The  physical  deflocculating  (pulverizing)  effect 
of  soluble  organic  matter  on  clay. 

Every  one  has  seen  fragments  of  rock  with  bright 
glassy  fragments  of  quartz  or  silica  associated  with 
slightly  duller  particles  and  others  black  in  color.  The 
less  glassy  white  or  pink  places  are  likely  feldspar, 
which  weathers  to  clay,  and  the  black  mineral  particles, 
on  weathering,  make  the  clay  reddish,  due  to  iron  oxide. 

As  the  rocks  break  up,  clay  is  formed  from  feldspar, 
and  particles  of  silica  are  separated  and  form  sand, 
especially  after  they  have  been  split  up  into  smaller 
pieces  by  changes  in  temperature,  etc.  We  often  see 
strata  of  rock  in  cliff  faces  or  railway  cuts  where 
the  rock  is  perceptibly  crumbling  and  becoming  soil. 
Sometimes  the  change  is  so  slow  that  one  does  not 
notice  it.  In  other  instances  we  can  from  season  to 
season  note  the  changes  wrought  by  nature.  If  all  the 
surface  soil  were  removed  to  the  underlying  rock  at 
any  point,  the  agencies  of  mineral  decay  would  in  a  few 
years  or  centuries,  or  other  periods  of  time,  produce 
the  accustomed  result  of  soil  formation.  In  almost  all 
the  advanced  stages  of  this  decay  we  can  see  the  par- 
ticles of  silica  (sand)  or  mica  separating  from  the  de- 


SOIL  AND  ITS  CONSERVATION  161 

composing  rock.  This  soil  production  is  noticeable  in 
the  very  early  spring.  In  many  cases  there  are  small 
avalanches  of  decomposed  rock  running  down  over 
snow-banks  from  the  rock  faces  above.  This  is  partic- 
ularly noticeable  in  railway  cuts  in  February  or  March. 

Burroughs  refers  again  to  the  soil  in  his  beautiful 
yet  terse  manner:  "The  history  of  the  soil  which  we 
turn  with  our  spade,  stamp  with  our  shoes,  covers  mill- 
ions upon  millions  of  years.  It  is  the  ashes  of  the  moun- 
tains, the  leavings  of  untold  generations  of  animal  and 
vegetable  life.  It  came  out  of  the  sea;  it  drifted  from 
the  heavens ;  it  flowed  out  of  the  fiery  heart  of  the  globe ; 
it  has  been  worked  over  and  over  by  frost  and  flood, 
blown  by  winds,  shovelled  by  ice — indeed,  the  soil  itself 
is  an  evolution,  as  much  so  as  the  life  upon  it." 

Sand  in  its  purest  form  is  silica,  but  any  fine  pieces 
of  rock  are  familiarly  known  as  sand.  The  chief  prac- 
tical difference  between  silica  Sand  and  other  sand  is 
that  silica  is  not  very  alterable,  whilst  complex  silicates 
are  liable  to  disintegration.  Sand  is  generally  white 
unless  it  contains  iron. 

Clay  and  sand  are  two  essentials  of  soil,  and  we 
have  just  seen  how  they  are  formed.  Other  minerals 
than  silica,  necessary  to  soil  formation,  contain  lime, 
iron,  magnesia,  phosphoric  acid,  potassium,  sodium, 
manganese,  sulphates,  chlorides,  etc.,  which  are  needed 
to  sustain  plant  life.  While  all  the  mineral  substances 
11 


162  CHEMISTRY  OF  FAMILIAR  THINGS 

just  mentioned  are  necessary  for  proper  plant  de- 
velopment in  general,  it  has  been  found  that  there  are 
three  substances  that  no  plant  can  do  without.  LThey 
are  potassium  salts,  phosphates,  and  nitrogen,  chiefly 
in  the  form  of  nitrates.  The  first  two  of  these  sub- 
stances are  supplied  from  rock  sources  and  exist  in  the 
soil  chiefly  as  more  or  less  fine  rock  particles  and  a 
smaller  amount  in  water  solution.  The  nitrogen  comes 
directly  or  indirectly  from  the  air.  The  particles  of 
rock  containing  these  valuable  fertilizing  substances  are 
the  reserve  store,  while  the  soluble  quantities  are  for 
immediate  use. 

From  time  immemorial  it  had  been  known  that  soil 
continuously  cultivated,  especially  by  one  crop,  became 
exhausted,  but  the  reason  was  not  known  for  a  long 
time.  Although  in  the  more  recent  periods  it  was  known 
that  plant  substance  contained  mineral  matter,  it  was 
thought  to  be  incidental.  Of  course,  ground  was  culti- 
vated and  in  a  way  it  was  fertilized,  but  the  reason  for 
the  latter  was  not  clear.  Farmers  knew  that  if  the 
ground  lay  fallow  a  year  it  would  produce  more,  or  that 
if  the  crops  were  rotated  it  would  produce  regularly, 
especially  if  animal  and  vegetable  refuse  were  used  on 
the  fields.  It  was  the  great  German  chemist,  Justus  von 
Liebig,  who  first  realized  that  plant  life  always  with- 
drew certain  constituents  from  the  soil,  and  showed  that 
if  the  most  fundamental  mineral  foods  were  restored 


SOIL  AND  ITS  CONSERVATION  163 

there  would  not  have  to  be  periods  of  idleness  to  re- 
juvenate it. 

Clay  alone  would  not  constitute  soil.  Sand  alone, 
and  even  clay  and  sand,  would  not  constitute  soil.  A 
third  essential  ingredient  is  the  decomposed  organic 
matter  or  plant  residues  (roots,  etc.)  that  have  become 
degraded  and  form  the  so-called  humus.  This  is  an- 
other of  the  many  evidences  of  nature's  conservation  of 
her  resources.  Plants  grow,  bloom,  are  reproduced 
by  seeds,  etc.,  and  the  old  tissues  rot  in  the  earth  as  they 
are  pressed  into  the  soil,  and,  as  soil  constituents,  form 
new  and  never-ending  cycles  of  beauty  and  usefulness. 
The  value  of  humus  lies  chiefly  in  its  water-holding 
capacity.  It  gives  a  dark  color  to  the  soil,  which  would 
otherwise  be  white  or  shading  to  red,  due  to  the  presence 
of  iron.  Leaf  mould  and  wood  earth  are  largely  humus 
unless  they  have  become  mixed  with  clay  soil.  The  work 
of  worms  and  insects  effects  a  mixing  of  all  components. 

Lime  is  chiefly  of  value  in  that  it  neutralizes  the  acid 
qualities  of  the  humus  or  mimic  acids,  as  the  acid  prin- 
ciples of  humus  are  sometimes  called,  and  as  an  addi- 
tional property,  or  because  of  its  neutralizing  the 
humus,  it  tends  to  granulate  the  clay  and  thus  make  it 
more  valuable.  A  good  soil,  therefore,  is  a  combina- 
tion of  clay,  sand,  humus,  lime,  and  other  mineral  con- 
stituents, such  as  potassium  salts  and  phosphates.  Gen- 
erally speaking,  good  soils  are  a  little  richer  in  sand 


164  CHEMISTRY  OF  FAMILIAR  THINGS 

than  in  clay,  and  if  there  is  over  50  per  cent,  of  clay 
the  soil  is  stiff  to  work.  Very  sandy  soils  may  have 
only  15  per  cent,  of  clay.  The  pore  space  should  be  30 
to  50  per  cent,  by  volume.  The  volume  of  pores  may 
be  determined  by  filling  a  quart  measure  with  soil  and 
noting  how  many  fluidounces  of  water  can  be  added 
without  overflowing,  after  air  has  been  displaced. 

Soils  are  examined  in  various  ways  to  determine 
their  composition.  Their  fineness  is  determined  by 
sieving  when  dry,  and  their  capacity  for  water,  both 
hygroscopic  and  total,  and  pore  space  are  estimated. 
They  are  chemically  examined  for  humus,  lime,  potash, 
and  phosphoric  acid,  and  these  tests  might  be  followed 
by  examination  for  bacteria  in  special  cases.  It  has 
recently  been  found  that  manganese  has  an  important 
catalytic  effect  upon  plant  growth.  Gabriel  Bertrand, 
in  France,  found  that  with  the  use  of  22  to  52.8  pounds 
of  manganese  sulphate  per  acre  various  crops  were 
increased  from  10  to  33  per  cent. 

In  addition  to  the  mineral  substances  mentioned  pre- 
viously,— namely,  silica,  alumina  (from  clay),  magne- 
sia, iron,  lime,  sulphur  (from  sulphates),  phosphorus 
(from  phosphates),  and  potassium, — plants  require  car- 
bon, hydrogen,  nitrogen,  and  oxygen.  The  carbon  comes 
from  carbon  dioxide  in  the  air,  the  oxygen  directly  from 
the  air,  and  the  nitrogen  also  comes  from  the  air  after 
being  converted  into  nitrate  by  means  of  bacteria. 


SOIL  AND  ITS  CONSERVATION  165 

There  are  many  times  as  much  necessary  mineral 
foods  for  plant  life  in  practically  all  soils  as  the  cus- 
tomary crops  require  for  a  season's  growth.  It  may 
average  from  50  to  100  times  the  quantity,  but  the  entire 
amount  is  only  slowly  made  available  by  the  action 
of  carbon  dioxide  gas  or  its  weak  union  with  water, 
which  is  called  carbonic  acid,  and  possibly  other  agen- 
cies. Carbon  dioxide  is  always  coming  off  from  culti- 
vated soil  as  it  is  formed  from  decomposing  organic 
matter.  A  little  of  it  is  used  before  total  elimination 
to  free  the  phosphoric  acid  and  to  break  up  the  feldspar, 
thus  forming  kaolin  (clay)  and  soluble  potassium  salts, 
and  the  rest  of  it  comes  from  the  surface  of  the  soil, 
and,  because  of  the  fortunate  provision  of  nature  in 
giving  a  greater  weight  to  this  gas  than  air,  it  tends  to 
stay  close  to  the  ground,  where  the  plants  can  absorb 
it  with  their  leaves  to  best  advantage  and  thus  obtain 
the  carbon  they  need  for  their  growth.  There  is  thus 
the  two-fold  value  of  plowing  under  plant  refuse, — 
it  forms  humus  which  retains  moisture  and  it  gives  off 
large  quantities  of  carbon  dioxide  to  feed  the  tops  of 
new  plants.  Even  for  lawn  grass,  when  the  mowing  is 
done  frequently  before  it  has  grown  more  than  two 
or  three  inches,  it  is  beneficial  to  let  the  tops  fall  and 
make  humus  around  the  roots,  and  there  will  be  less 
danger  of  the  grass  being  killed  or  parched  in  dry 
weather.  From  time  to  time,  however,  most  soils  re- 


166  CHEMISTRY  OF  FAMILIAR  THINGS 

quire  lime  to  neutralize  the  humic  acids  formed,  mak- 
ing neutral  salts,  which  might  be  called  calcium  humate. 
This  soluble  organic  matter  is  undoubtedly  valuable  in 
loosening  the  clay  aggregates,  or  deflocculating  it,  as 
Acheson  does  his  graphite  for  lubricating  purposes. 

"Ways  to  tell  when  soil  is  very  acid  are :  (a)  It  turns 
moistened  blue  litmus  paper  quickly  red;  (b)  the  soil 
tends  to  be  dense  rather  than  crumbly;  (c)  weeds  grow 
very  rankly.  As  bacteria  will  be  shown  to  be  needful 
for  plant  life,  and  as  scientists  have  found  that  in  most 
cases  useful  plants  develop  better  in  neutral  than  in 
acid  media,  it  is  in  every  way  desirable  to  keep  the  soil 
nearly  neutral.  Keeping  soil  neutral  is  easier  done  on 
high  ground  than  in  low,  where  organic  acids  from  de- 
composing vegetable  matter  remain  instead  of  being 
split  up  into  carbon  dioxide  gas  and  water. 

We  have  to  depend  largely  upon  nature  to  supply 
what  is  needed  for  the  growth  of  plants,  and  her  part 
is  done  wonderfully  well.  There  are  few  parts  of  the 
United  States  that  do  not  have  sufficient  rainfall  for 
bountiful  crops  when  care  is  taken  to  conserve  the 
moisture  during  moderately  dry  as  well  as  in  the  very 
driest  seasons.  If  it  is  conserved  during  moderately 
dry  seasons,  the  problem  is  less  difficult  in  the  driest 
period.  There  are  also  few  sections  of  the  country 
where  rains  are  so  frequent  that  no  care  need  be  ex- 
ercised to  conserve  water.  The  soil  holds  water  very 


SOIL  AND  ITS  CONSERVATION  167 

well  for  plant  use  when  loose  and  open,  but  if  packed 
and  the  grains  of  clay  and  sand  are  in  close  proximity, 
water  comes  up  to  the  surface  by  capillarity  too  rapidly 
and  passes  off  into  the  air.  Every  one  has  observed 
the  phenomena  of  capillarity  in  the  home — (a)  how 
the  blotter  absorbs  ink;  (b)  how  a  sponge  absorbs 
water;  (e)  how  oil  rises  in  a  wick;  (d)  how  a  dry  cloth 
laid  in  a  basin  of  water  will  become  wet,  and,  if  the 
cloth  extends  over  the  edge  of  the  basin  and  hangs  down, 
water  may  drop  from  the  end. 

Soil  moisture  and  the  soil  atmosphere  play  a  very 
important  role.  Moisture  in  the  soil  normally  is  only 
on  the  surface  of  the  particles.  When  the  soil  is  satu- 
rated, however,  it  sinks  by  gravity  and  draws  down  the 
soil  atmosphere,  rich  in  carbon  dioxide.  The  carbon 
dioxide  dissolves  in  water,  and  this  acid  solution  attacks 
the  feldspar  and  lime  rocks.  When  the  soil  dries  out 
at  the  surface  the  soil  solution  rises  by  capillarity  with 
fresh  mineral  salts  in  solution.  Moisture  will  steadily 
pass  off  from  the  soil  by  evaporation  after  a  rain,  but, 
if  the  soil  be  pulverized  a  day  or  two  after  the  rain  and 
stirred  up  from  time  to  time,  enough  moisture  will 
nearly  always  remain  until  fresh  rains  come.  The 
amount  of  water  plants  use  that  is  not  in  their  substance 
at  maturity  is  enormous,  probably  a  hundred  times  that 
used.  Large-leafed  plants  such  as  cabbages  will  give  off 
tons  of  water  per  day  per  acre,  and  this  and  more  must 


168  CHEMISTRY  OF  FAMILIAR  THINGS 

be  found  by  the  roots.  Plant  roots  will  seek  the  best 
water  levels,  and  in  dry  weather  a  little  surface  water- 
ing will  do  more  harm  than  good,  as  it  will  tend  to  make 
the  roots  turn  up  to  the  moist  surface  layer  instead  of 
continuing  a  downward  growth. 

Analyses  are  often  made  of  a  soil  to  determine  the 
available  and  total  potassium  salts,  nitrates,  and  phos- 
phates, and  the  results  are  valuable  only  when  applied 
to  a  particular  soil  and  locality.  Two  fields  on  the 
same  farm  may  have  equal  fertility,  with  different 
amounts  of  plant  food,  because  of  the  different  charac- 
ter of  the  soils.  The  following  figures  are  probably  ap- 
proximate percentages  of  the  chief  constituents  of  plant 
food  in  good  soil: 

Plant  Food                                 Symbol  Percentages 

Nitrogen (N)  0.16  to  0.20 

Phosphoric  acid (PaOs)  0.20  to  0.40 

Potash (K20)  0.40  to  0.50 

Carbonate  of  lime. (CaCQs)  1.00  to  3.00 

A  good  rule  in  fertilizing  is  to  add  to  all  ground  such 
an  amount  per  year  of  manure  or  fertilizer  that  the 
available  plant  food  shall  not  diminish.  Fertilizers  are 
generally  turned  under  the  ground  to  prevent  their 
being  washed  away  and  to  be  where  required  by  the 
plant  roots.  It  is  difficult,  however,  for  water  to  wash 
away  fertilizing  constituents  when  mixed  with  earth, 
for  a  reason  to  be  considered.  Enormous  loss  is  sus- 
tained annually  in  the  tlnited  States  and  other  countries 


SOIL  AND  ITS  CONSERVATION  169 

by  soil  erosion  where  the  best  loam  is  carried  away  by 
the  streams  and  rivers,  but  it  is  a  case  of  bodily  removal 
of  soil  and  not  a  case  of  dissolving  out  potash  and  phos- 
phates. If  the  soil  did  not  have  a  property  whereby 
it  could  hold  the  valuable  constituents,  the  rains 
would  wash  all  the  fertilizing  elements  out  of  the  soil, 
and  the  underground  streams  which  emerge  at  low 
levels,  as  springs,  would  be  rich  in  plant  food.  Water 
analyses  do  not  show  this.  There  are  various  proofs 
that  show  this  property  of  the  soil  for  holding  plant 
food,  which  is  called  adsorption.  For  example,  many 
people,  including  the  author,  have  drunk  very  pleasing 
water  drawn  from  artesian  wells  within  a  few  feet  of  the 
ocean  itself.  Why  is  it  not  brackish?  Chemists  have 
found  that  clay  and  fine  sand  have  some  kind  of  a 
physical  or  chemical  attraction  for  these  soluble  salts. 
So  the  water  can  pass  through  the  soil  and  leave  the 
soluble  substance  for  plant  nourishment. 

The  most  important  consideration  of  the  farmer  and 
the  truck  raiser,  and  one  of  the  most  practical  for  the 
amateur  agriculturists,  is  the  study  of  fertilizers  to  de- 
termine the  best  to  use  under  general  and  special  condi- 
tions. Those  much  interested  in  the  study  of  fertilizers 
can  secure  all  the  information  they  may  require  from 
State  and  national  authorities,  as  Bulletins  have  been 
published  from  time  to  time  that  go  into  all  phases  of 
the  subject.  The  Secretary  of  Agriculture  will  send 


170  CHEMISTRY  OF  FAMILIAR  THINGS 

lists  of  publications  to  those  who  request  them.  State 
and  national  laws  on  this  subject  have  put  the  sale  of 
fertilizers  upon  a  perfectly  plain  and  fair  basis,  as  it  is 
required  in  this  country  that  the  percentages  of  the 
active  ingredients  be  marked  on  each  bag  or  package. 
Competition  has  made  the  prices  proportional  to  the 
composition. 

The  three  primal  requisites  for  plant  growth,  other 
than  suitable  soil  and  proper  cultivation,  are  potassium, 
phosphoric  acid  and  nitrogen,  chemically  combined. 
There  are  a  great  many  kinds  of  fertilizers  and  all  are 
sold  at  so  much  per  unit  of  each  ingredient.  The  best- 
known  and  probably  most-used  fertilizer  is  ordinary 
barnyard  manure.  It  does  not  contain  as  much  plant 
food  as  the  best  commercial  fertilizers,  but  it  is  very  ef- 
fective because  of  the  organic  matter  it  contains,  which 
dilutes  the  active  substances  and  tends  to  form  a  soil 
rich  in  humus  (bordering  on  bituminous  matter).  Any 
fertilizer  in  concentrated  condition  is  liable  to  kill  plants 
if  it  gets  in  their  roots,  as  any  very  strong  chemicals 
would  do.  A  very  concentrated  form  of  natural  manure 
is  sheep  manure.  Guano  from  Peru  is  a  fertilizer  con- 
sisting of  the  manure  and  decomposed  carcasses  of  sea- 
fowl,  much  used  in  the  past  but  fast  being  superseded 
by  artificial  fertilizers.  Fresh,  dry,  ground  carcasses 
of  fish  are  used  chiefly  for  their  nitrogen.  Bone  meal 
is  chiefly  valuable  for  phosphoric  acid  and  nitrogen, 


SOIL  AND  ITS  CONSERVATION  171 

while  leather  scraps  and  powdered  hoofs  and  horns  are 
used  for  nitrogen  alone.  The  most  concentrated  fer- 
tilizers for  supplying  nitrogen  are  nitrates  of  soda  and 
lime,  and  ammonium  salts.  A  few  analyses  of  fertil- 
izers are  given  in  the  footnotes.3 

In  a  few  words,  the  effects  of  the  several  ingredients 
of  fertilizers  are:  nitrogen  (ammonia)  causes  rapid 
vegetation;  phosphoric  acid  and  potash  are  needed  for 
the  plant  cells  and  sap,  and  must  be  supplied  as  re- 
quired. Nitrogen  may  be  supplied  as  organic  matter, 
as  in  fish  remains  (protein  nitrogen),  as  ammonia,  and 
as  nitrate.  Phosphoric  acid  (P205)  comes  in  artificial 
fertilizers  as  an  acid  calcium  phosphate,  which  is  made 
by  adding  sulphuric  acid  to  phosphate  rock.  Part  of 
the  phosphoric  acid  in  commercial  fertilizers  is  soluble, 
part  insoluble,  and  another  part  is  called  reverted, 
which  slowly  becomes  soluble.  It,  of  course,  is  only 
valuable  when  soluble  or  slowly  available  in  the  soil. 

The  importance  to  the  farmer  of  saving  the  liquid 
portion  of  the  manure  is  shown  in  the  following  extract 


Phosphoric  acid  (P2O6)    Nitrogen  (N)          Potash  (KzO) 

a  Farmyard    manure  ....     0.50  per  cent.  0.50  per  cent.      0.30  per  cent. 

Peruvian    guano 12.14  9.14                       1.00 

Dried  fish 10.15  6.12 

Sodium  nitrate    19.00 

Oil  cake  (castor)    1.5-3  4.7                        1.0-2.0 

Bone  meal    20     -30  2.5 

Mineral  potash 65-70 

Phosphate  rock 30      -40 


172  CHEMISTRY  OF  FAMILIAR  THINGS 

from  a  pamphlet  published  by  Dr.  Samuel  G.  Dixon, 
Health  Commissioner  of  Pennsylvania:  "If  you  do  not 
retain  the  natural  liquids  and  those  dissolved  out  by 
the  rains,  your  crops  will  fall  short  or  you  will  have 
to  take  the  money  and  purchase  artificial  fertilizers 
which  do  not  take  the  place  of  good,  well-kept  manure. 
You  will  not  get  the  humus,  nor  will  you  keep  up  the 
biological  standard  and  general  physical  conditions  of 
your  soil.  If  you  will  keep  the  manure  in  water-tight 
pits,  well  packed  and  moist,  your  expenses  will  come 
back  to  you  tenfold,  and  at  the  same  time  you  will  be 
your  brother's  keeper  by  preventing  your  sewage  from 
getting  into  his  water  supply  and  making  him  sick  with, 
maybe,  one  or  another  of  many  intestinal  diseases.  You 
can  co-operate  with  the  health  authorities,  make  more 
out  of  the  land  and  save  others  and  yourselves  much 
sickness,  sorrow, — yes,  death. " 

The  final  consideration  under  this  subject  is  that 
of  the  bacteria  and  larger  forms  of  organisms  of  the 
soil.  We  have  known  for  some  time  that  worms  loosen 
up  the  soil  and  distribute  the  plant  food.  Their  in- 
fluence is  probably  chemical  as  well  as  physical  by 
supplying  soluble  organic  matter.  The  chief  considera- 
tion here,  however,  lies  with  the  millions  of  bacteria 
that  are  at  one  time  found  in  an  amount  of  soil  of  no 
bigger  volume  than  a  moderate-sized  earthworm.  From 
500,000  to  1,000,000  bacteria  are  found  in  summer  in  a 


SOIL  AND  ITS  CONSERVATION  173 

single  grain  weight  of  soil.  Besides  bacteria,  there  are 
yeasts,  moulds,  fungi,  protozoa,  amoeba,  nematodes,  and, 
finally,  worms.  Some  of  these  organisms  are  so  small 
that  the  most  powerful  microscopes  can  only  see  them 
under  favorable  circumstances.  The  protozoa  and 
amoeba  are  larger  than  the  bacteria,  and  the  nematodes 
are  very  small  worm-like  animals.  The  reason  all 
these  are  mentioned  is  because  they  all  have  chemical 
influence  on  the  soil.  Some  are  the  prey  of  others,  so 
that  the  numbers  of  each  variety  are  limited  by  their 
racial  fights  for  existence.  The  yeasts,  moulds,  and 
fungi  are  probably  mostly  concerned  with  the  first  steps 
of  the  reduction  of  organic  matter  to  humus.  The  most 
important  cycle  of  operations  is  in  the  change  of  pro- 
tein (nitrogenous  organic  matter),  first  by  one  set  of 
bacteria  into  amino  acids,  then  into  ammonia  by  an- 
other  group;  another  group  form  nitrites  from  the 
ammonia,  and,  lastly,  others,  called  nitrifying  bacteria, 
change  the  nitrites  into  nitrates,  which  are  utilized  by 
the  plants.  This  cycle  of  change  is  dependent  upon  a 
proper  balance  of  animal  life  in  the  soil,  which  is  depen- 
dent upon  the  existence  of  all  the  organisms  mentioned 
and  upon  moisture,  warmth,  and  aeration  of  the  soil.  If 
the  ground  is  watersoaked,  there  flourish  a  set  of  bac- 
teria which  are  denitrifying.  Therefore,  it  is  very 
necessary  to  have  the  soil  open  so  that  air  can  get  in  to 
aid  the  nitrifying  bacteria. 


174 


CHEMISTRY  OF  FAMILIAR  THINGS 


Leguminous  and  some  other  plants  through 
bacterial  action 


Atmospheric 
nitrogen 

Vegetable  life 

Organic  nitro- 
gen compounds 
in  plants  and 
animals 

Dentrifyingmicro- 
•<-  organisms  and  other  dis  

Nitric 
acid 

integrating  influences. 

1 

Nitration 
by  micro- 
organisms 


x^uaij£co  AAJL  vege- 
table and  animal 
organisms  f  o  1  - 
lowed  by  decom- 
posi  tion  by 
m  i  c  r  o-o  r  g  a  n  - 
isms,  etc. 


Nitrous 
acid 

Conversion 
into  nitrous 

Ammonia 

acid  by  micro- 
organisms 

There  is  another  important  kind  of  bacterium  that  is 
not  concerned  in  this  nitrogen  cycle,  but  seems  to  have  a 
new  and  improved  process  for  making  nitrates.  Instead 
of  employing  three  or  more  races  of  bacteria  to  make  the 
desired  chemical,  these  recently  discovered  bacteria 
make  it  apparently  by  themselves,  directly  out  of  the 
nitrogen  and  oxygen  of  the  air.  Their  life  is  distinctly 
apart  from  the  dense  and  the  heterogeneous  world  of 
soil  life,  as  they  are  housed  in  cavities  and  nodules 
formed  in  the  roots  of  certain  plants,  chiefly  the  legumi- 
nous plants,  such  as  peas  and  beans,  and  also  in  clover 
and  alfalfa.  These  bacteria  not  only  greatly  assist  the 
growth  of  these  plants,  but,  due  to  the  excess  of  nitrates 
formed  over  what  the  plants  use,  the  ground  is  more 
fertile  after  these  crops  are  grown  than  before.  This  is 
one  reason  why  clover  is  a  good  crop  to  alternate  with 
grain.  Barren  soils  can  be  improved  by  an  inoculation 
with  these  bacteria  by  spreading  in  the  place  desired 


PLATE  XVIII. 


Alfalfa,  showing  root  nodules  encasing  nitrifying  bacteria. 


SOIL  AND  ITS  CONSERVATION  175 

some  soil  from  where  these  nitrogen-fixing  bacteria 
have  been  abundant.  About  half  a  ton  of  this  soil  per 
acre  is  sufficient,  which  amounts  to  a  mere  sprinkling. 
Cultures  from  growths  in  gelatin  are  also  used  as  seed 
instead  of  spreading  soil.  It  may  take  several  years 
before  the  benefit  of  this  inoculation  is  apparent. 

There  are  bacteria  in  the  soil  that  do  not  exactly 
concern  the  chemist,  but  a  few  words  may  be  said  about 
them  here.  The  bacillus  of  tetanus  is  found  in  the  soil, 
particularly  in  layers  below  the  influence  of  the  sun's 
rays.  The  same  is  often  true  of  typhoid  and  diphtheria 
bacteria.  The  former  has  been  known  to  flourish  and 
spread  in  damp,  dark,  warm  soil.  "Well  cultivated, 
aerated  soils  are  inimical  to  these  bacteria,  as  sun  and 
air  are  fatal  to  their  growth. 

Mght-soil  and  cesspool  contents  should  not  be  used 
in  truck  patches,  because  of  the  nearness  to  the  house, 
the  danger  to  persons  working  in  them,  the  danger  of 
contaminating  green,  uncooked  vegetables,  and  the 
nearness  to  wells  which  this  matter  might  pollute. 
Their  benefit  would  be  slight  and  the  risk  of  their  use 
so  great  that  the  fertilizing  value  might  as  well  be 
entirely  ignored. 

The  regular  growth  of  the  plant  is  very  much  the 
same  as  it  is  with  animals,  although  the  means  of  nu- 
trition are  different.  In  the  young  plant,  sprouting 
from  the  seed,  the  starch,  protein,  and  fat  stored  there 


176  CHEMISTRY  OF  FAMILIAR  THINGS 

feed  the  growing  stem  and  branches  so  long  as  the  food 
lasts  or  until  there  is  enough  chlorophyll  to  make  the 
food  in  the  leaves.  Plants  have  to  form  their  own  food 
from  the  air  with  the  aid  of  chlorophyll  from  the  energy 
derived  from  the  sun's  rays  in  conjunction  with  water 
of  carbon  dioxide  and  inorganic  salts.  The  carbon 
dioxide  of  the  air  and  water  make  formaldehyde.  The 
condensation  of  formaldehyde  produces  the  sugar  which 
is  changed  by  plant  enzymes  into  starch,  pectin,  or  cellu- 
lose. The  nitrogen  of  the  air  is  changed  by  bacteria  into 
nitrate,  which  the  plant  changes,  probably  in  its  roots, 
to  protein  material,  although  it  may  be  that  nitrogen  is 
also  absorbed  by  the  leaves  to  form  protein. 


CHAPTER  XIII 

t 

FOOD    ELEMENTS   AND    FOOD    CLASSES 

ANIMALS  depend,  in  general,  upon  vegetation  for 
their  food,  although  some  animals  take  short  cuts  and 
save  time  in  eating  and  in  digestion  by  consuming  flesh 
itself.  Animals  get  only  salts  and  water  from  inor- 
ganic sources. 

The  natural  inclination  or  instinct  and  the  ex- 
perience of  countless  past  generations  have  shown  us 
what  to  consider  as  food.  The  chemist  in  most  cases  con- 
firms the  reasonableness  of  the  selections  made  and 
shows  from  his  analyses  and  tests  which  foods  are  best 
for  special  requirements.  Chemistry  is  important  in 
detecting  impure  and  adulterated  foods. 

Food  is  required  to  supply  the  force  for  the  un- 
conscious work  of  pumping  the  blood  and  breathing 
and  also  the  requirements  of  the  voluntary  muscles, 
and,  as  incident  to  these  activities  and  independent  of 
them  if  need  be,  to  supply  heat  to  maintain  the  body 
temperature  of  98.6°  F.  With  some  difficulty  we  can 
maintain  our  houses  at  fairly  uniform  temperatures, 
but  we  never  succeed  to  the  fine  point  that  is  maintained 
in  our  bodies, — accurate  to  a  tenth  of  a  degree.  Of 
course,  this  is  only  accomplished  by  means  of  an  ab- 
12  177 


178  CHEMISTRY  OF  FAMILIAR  THINGS 

solutely  dependable  automatic  regulator,  as  we  nor- 
mally replenish  the  bodily  fires  with  fuel  only  three 
times  in  twenty-four  hours  and  yet  the  temperature 
does  not  vary. 

The  exact  way  food  acts  to  create  heat  in  the  body 
has  been  shrouded  in  some  mystery,  because  of  the  dif- 
ferent classes  of  food  materials  which  create  heat.  Pro- 
tein material  is  quite  different  chemically  from  carbo- 
hydrates, and  fat  is  another  class  differing  from  the 
other  two,  yet  all  three  classes  are  capable  of  produc- 
ing heat.  It  would  take  too  much  space  even  to  outline 
the  different  theories  that  have  been  advanced  to  solve 
this  wonderful  cycle  of  change  in  the  assimilation  of 
food  and  creation  of  heat  and  energy.  We  know  these 
substances  are  more  or  less  interchangeable,  except  that 
only  protein  can  form  muscular  tissue  and  repair  the 
same. 

It  has  been  found  possible  to  measure  the  heat  that 
food  substances  are  capable  of  forming  on  combustion 
with  oxygen  in  two  ways ;  both  consist  in  the  use  of 
calorimeters,  or  heat-measuring  instruments.  One 
way  is  outside  of  the  body,  in  which  a  very  small  but 
definite  weight  of  the  dry  food  substance  is  burned  in 
oxygen  and  the  heat  formed  is  absorbed  in  water  and 
measured  by  the  consequent  rise  in  temperature  of  the 
water.  The  other  way  is  by  the  use  of  a  calorimeter  so 
large  that  a  man  can  be  contained  in  it,  and,  as  he  eats, 


FOOD  ELEMENTS  AND  FOOD  CLASSES  179 

sleeps,  moves,  reads,  etc.,  the  heat  that  is  radiated  from 
his  body  is  measured  by  delicate  thermometers.  Of 
course,  unavoidable  heat  losses  are  measured,  so  that 
the  calculation  may  be  dependable.  In  the  illustration 
opposite  page  178  the  calorimeter  holding  the  human 
furnace,  the  heat  of  which  is  to  be  measured,  looks 
like  a  closet  with  a  window  in  it  to  the  left  of  the  cut. 

Digestion  consists  of  a  series  of  chemical  changes 
which  are  designed  by  nature  to  dissolve  the  food  or 
mechanically  emulsify  it  with  water,  as  food  must  be 
dissolved  or  emulsified  to  be  assimilated,  and  the  cells 
of  the  body  are  composed  largely  of  water.  "Water  is  an 
important  food  or  food  accessory.  As  S.  Solis  Cohen 
has  said,  "The  cells  of  the  body  are  aquatic  in  their 
habit. ' '  Sixty  to  seventy  per  cent,  of  the  body  is  water. 

In  nearly  every  process  of  digestion  the  change  is 
brought  about  by  substances,  called  enzymes,  made  in 
glands  of  the  body.  Enzymes  do  similar  work  of  diges- 
tion in  the  vegetable  world.  We  all  know  of  the  enzyme 
called  diastase  in  the  young  shoots  of  barley.  Of  course, 
there  are  enzymes  in  all  young  shoots  from  seeds. 
These  enzymes  digest  the  starch  in  the  seeds,  say  of  bar- 
ley or  corn,  and  convert  it  into  soluble  sugars,  which  are 
carried  through  the  tissues  of  the  young  plant  and  de- 
posited as  pectin  or  cellulose  to  form  the  skeleton  or 
framework  of  the  plant.  After  the  leaves  are  formed 
this  starch  is  not  needed,  as  carbohydrates  are  built  up 


180  CHEMISTRY  OF  FAMILIAR  THINGS 

from  the  carbon  dioxide  of  the  air  and  water  by  the  in- 
fluence of  sunlight  and  in  the  presence  of  the  catalytic 
substance  known  as  chlorophyll,  or  the  green  coloring 
matter  of  the  leaves.  A  catalytic  substance  is  one  which 
induces  a  chemical  change  without  entering  into  the 
reaction  itself  by  giving  any  component  to  the  new  sub- 
stance formed.  Enzymes  are  of  this  general  character. 

The  different  food  classes  are  digested  differently. 
Starch,  which  is  the  most  important  food  member  of  the 
carbohydrate  family,  is  acted  upon  first  in  the  mouth 
under  the  influence  of  ptyalin.  According  to  Davis,1  this 
action  is  retarded  by  cold  liquids  and  acids.  Water 
had  best  not  be  taken  in  quantity  during  the  mastica- 
tion of  carbohydrates,  and  acid  fruits  should  rather 
follow  than  precede  the  meal.  In  most  cases  the  food 
is  not  in  the  mouth  long  enough  for  much  digestion  to 
take  place,  and  no  change  in  starch  is  effected  in  the 
stomach  except  mechanical  disintegration,  due  to  agita- 
tion and  the  attack  of  the  stomach  juices  upon  the  pro- 
tein. Carbohydrates  are  chiefly  digested  in  the  small 
intestine  by  amylopsm,  an  enzyme.  All  carbohydrates 
finally  are  changed  into  dextrose,  which  enters  the 
blood. 

Fats  and  oils  are  acted  upon  by  the  pancreatic  juice 
(pancreatin)  and  are  then  saponified  and  emulsified  in 
the  intestine  by  the  enzyme  steapsin.  They  are  carried 
Jy  the  blood  to  the  places  where  deposited  or  stored  for 

•     * "  Dietotherapy  and  Food  in  Health/'  by  Nathan  S.  Davis. 


FOOD  ELEMENTS  AND  FOOD  CLASSES  181 

continual  combustion  to  carbon  dioxide  and  water  and 
liberating  their  definite  quantities  of  heat  during  the 
process. 

In  the  case  of  protein  digestion  no  change  is  effected 
in  the  mouth.  In  the  stomach  acid  albumens  are  formed 
by  the  hydrochloric  acid  of  the  gastric  juice  and  then 
all  are  changed  into  peptones  by  the  action  of  pepsin. 
What  protein  escapes  digestion  and  absorption  in  the 
stomach  is  formed  first  into  alkali  albumen  at  the  en- 
trance of  the  intestine  and  then  acted  upon  by  the 
enzyme  trypsin,  to  complete  the  digestion  and  allow  of 
the  absorption  of  the  food  elements.  There  are  various 
influences  that  the  different  kinds  of  food  have  upon 
each  other  during  digestion.  If  protein  food  is  taken 
alone  and  escapes  digestion  in  the  stomach,  a  good  deal 
may  be  lost  by  bacterial  decomposition  in  the  intestines, 
which  are  in  large  part  alkaline  and  favor  bacterial  ac- 
tivity. The  use  of  mixed  diet  with  carbohydrate  food 
minimizes  this  occurrence,  as  acids  are  formed  during 
the  course  of  digestion  of  carbohydrates  which  render 
the  intestinal  tract  acid.  This  inhibits  the  growth  of 
organisms  that  would  live  at  the  expense  of  the  protein. 
A  fetid  odor  of  the  intestines  is  often  an  indication 
of  bacterial  putrefaction  of  protein  matter  therein, 
due  to  a  too  exclusive  meat  diet. 

Fat  influences  the  digestion  of  protein  and  carbohy- 
drates by  enclosing  particles  so  that  the  aqueous  jui 
do  not  readily  attack  them.    This  is  the  chief  reaso 


182  CHEMISTRY  OF  FAMILIAR  THINGS 

why  fried  food  is  often  indigestible.  Beadily  emulsi- 
fiable  fats,  like  butter,  cream,  and  olive  oil,  are  not 
so  detrimental  to  proper  protein  and  carbohydrate  di- 
gestion, as  they  are  easier  separated  by  the  steapsin. 

Protein  is  the  food  substance  or  class  of  substances 
containing  nitrogen,  such  as  lean  meat,  the  albumen  of 
eggs,  the  albumen  and  casein  of  milk,  and  that  part  of 
dry  vegetable  substances  which  is  not  oil,  carbohydrate, 
or  mineral  matter.  Carbohydrates  are  substances  that 
do  not  contain  nitrogen,  and  are  not  fats  and  oils.  They 
contain  carbon  and  hydrogen,  with  enough  oxygen  to 
form  water  with  the  hydrogen.  As  hydrogen  could  only 
give  energy  by  burning  to  form  water,  the  only  energy 
that  carbohydrates  have  is  the  potential  energy  of  the 
carbon.  Fats  are  glycerides  of  organic  acids.  They 
contain  no  nitrogen,  but  have  both  carbon  and  hydro- 
gen susceptible  of  oxidation.  For  this  reason  they 
create  more  energy  in  the  body  than  protein  or  carbo- 
hydrates. 

The  natural  selection  by  mankind  has  indicated  to 
investigators  the  best  combination  of  food  elements. 
Experiments  with  a  wide  range  of  combinations  have 
also  shown  that  this  certain  ratio  of  natural  selection 
is  really  the  most  practical  and  physiologically  the  most 
economical.  This  ratio  is  approximately : 

Fat 1  part    by  weight 

Protein   (digestible)    2.4  parts  by  weight 

Carbohydrate  (digestible)    *....    10.     parts  by  weight 


FOOD  ELEMENTS  AND  FOOD  CLASSES  183 

To  this  must  be  added  the  requisite  quantities  of 
water  and  mineral  matter.  The  ratio  of  fat,  protein, 
and  carbohydrates  varies  somewhat  from  infancy  to  old 
age.  More  protein  is  required  in  the  young  to  effect 
growth  than  in  the  mature,  and  in  the  case  of  the  aged 
there  is  so  little  muscular  action  that  extremely  little 
protein  is  required.  Lime  salts  are  required  in  abun- 
dance by  the  young  to  make  bones,  while  with  the  fully 
grown  very  little  are  needed. 

Nature  provides  the  proper  food  for  the  young  of 
all  species,  and  where  milk  from  the  mother  is  supplied 
it  has  a  composition  that  enables  the  young  to  develop 

properly. 

COMPOSITION  OF  MILK. 

Cow's  milk  Human  milk 

Water 87.3  per  cent.  87.4     per  cent. 

Fat    3.6  per  cent.  3.78  per  cent. 

Protein 3.8  per  cent.  2.29  per  cent. 

Milk  sugar 4.5  per  cent.  6.21  per  cent. 

Acid    0.1  per  cent.  none 

Ash   0.7  per  cent.  0.37  per  cent. 

Cow's  milk  can  be  given  to  infants,  but  modifica- 
tion is  desirable.  It  is  generally  diluted;  cream  is 
sometimes  added  to  supply  more  fat ;  milk  sugar  or  cane 
sugar  is  added  and  the  free  acid  is  neutralized  with 
lime  water.  The  calf,  for  whom  cow's  milk  was  in- 
tended, is  expected  to  grow  much  faster  than  the  child ; 
consequently  it  gets  more  protein  to  make  tissue  and 
more  mineral  matter  to  make  bone  and  less  carbohy- 


184  CHEMISTRY  OF  FAMILIAR  THINGS 

drates.  Lime  water  is  added  to  neutralize  the  free 
acid  in  cow's  milk  that  has  come  from  bacterial  action, 
although  the  fresher  the  milk  and  the  cleaner  the  dairy 
the  less  acid  to  be  neutralized.  It  might  be  asked, 
"What  is  the  function  of  the  barley  water  or  starchy 
liquid  from  oatmeal,  etc.,  that  is  sometimes  used?" 
This  is  added  to  prevent  dense  clots  in  the  stomach 
when  the  milk  is  curdled  by  the  acids  of  the  gastric 
juice.  Chemists  call  such  an  added  substance  a  "pro- 
tective colloid."  Gelatin  is  a  protective  colloid  and 
makes  ice-cream  smoother.  The  albumen  in  human 
milk  protects  the  casein  from  precipitation  or  curdling. 
There  is  no  one  article  of  food  that  combines  all  that 
is  requisite  to  the  system.  One  could  not  live  very  long 
on  nothing  but  carbohydrates  nor  on  fat  alone.  If  a 
person  takes  a  good  deal  of  exercise  he  might  get  along 
on  nothing  but  meat,  but  for  most  of  us  it  would  be  un- 
suitable. A  purely  vegetable  diet  would  serve  better 
than  one  of  meat  alone,  as  some  vegetable  foods  are 
nearly  balanced  in  the  nutritive  ratio.  Bread  has  suf- 
ficient protein,  carbohydrates,  and  mineral  matter,  but 
lacks  fat ;  however,  if  it  is  spread  with  butter  the  ratio  is 
about  right.  Most  people  in  good  circumstances  in  this 
country  eat  too  much  protein.  A  table  from  Olsen  gives 
rations  of  people  in  some  various  lines  of  activity.  The 
writer  does  not  wish  to  exaggerate  the  importance  of 


FOOD  ELEMENTS  AND  FOOD  CLASSES  185 

a  knowledge  of  total  calories  required  from  the  com- 
bustion of  food  and  of  balanced  rations,  as  most  people 
in  easy  circumstances  get  along  better  if  they  do  not  in- 
dulge their  appetite  so  freely,  but  for  the  benefit  of  the 
poor  and  less  well  informed  much  good  might  be  de- 
rived from  more  light  on  this  subject.  Men  suffering 
with  hunger  will  pay  their  last  piece  of  money  for  a  cup 
of  coffee,  with  but  a  trifle  of  nourishment,  when  they 
could  get  rolls,  baked  beans  or  meat  stew  with  more 
food  value  and  derive  real  benefit. 


SPECIAL  RATIONS 

Age  or  employment  Protein  Fat  Carbohydrates    Calories 

Average  adult  ....  100  grammes     100  grammes     420  grammes     3030 
Averasre  of  seven 


SPECIAL  RATIONS 

Prot 
LOO  gr£ 
Average  of  seven 

boat  crews 181  grammes     177  grammes    440  grammes    4085 

Foot-ball  team 181  grammes     292  grammes     577  grammes     5740 

United    States 

Army    85  grammes    280  grammes     500  grammes    4944 

Old   man    92  grammes       45  grammes     332  grammes     2149 

Old  woman   80  grammes      49  grammes    266  grammes     1875 

The  average  man  requires  food  that  will  give  about 
3000  calories  per  day.  Children  from  one  to  two  years 
of  age  require  24  per  cent,  of  the  food  to  be  protein, 
while  adults  need  only  about  16  per  cent.  This  is  due  to 
the  necessity  of  the  child  to  add  to  its  tissues  as  well  as 
repair  them. 

Another  table,  largely  from  Olsen,2  gives  the 
amounts  of  various  single  food  substances  that  will 
give  this  energy  or  fuel  value,  and  the  cost  of  each : 

2  "  Pure  Foods,"  by  J.  C.  Olsen. 


186 


CHEMISTRY  OF  FAMILIAR  THINGS 


COST  OF  A  DAILY  RATION  OF  A  SINGLE  FOOD  PEE  PERSON. 


Food 

Price 

Cost  of  4000  calories 

Flour  

...     3% 

cents 

per 

pound 

6.3 

cents 

Oatmeal    

...      5 

cents 

per 

pound 

8 

cents 

Rice  

...     8 

cents 

per 

pound 

15 

cents 

Sugar    

...     5 

cents 

per 

pound 

8 

cents 

Beef     

...20 

cents 

per 

pound 

58 

cents 

Milk    

...     9 

cents 

per 

quart 

20 

cents 

Eggs    

...40 

cents 

per 

dozen 

184 

cents 

Cheese  

...18 

cents 

per 

pound 

26 

cents 

Fish  

...14 

cents 

per 

pound 

101 

cents 

Potatoes  

...80 

cents 

per 

bushel 

12 

cents 

Cauliflower  .  .  . 

...15 

cents 

per 

pound 

215 

cents 

Onions  

...14 

cents 

per 

pound 

215 

cents 

Strawberries    . 

...13 

cents 

per 

pound 

250 

cents 

Butter  

...35 

cents 

per 

pound 

29 

cents 

Olive  oil  

..   250 

cents 

per 

gallon 

23 

cents 

Bananas    

...15 

cents 

per 

dozen 

40 

cents 

Oysters   

...12 

cents 

per 

dozen 

553 

cents 

Food  materials  are  not  completely  absorbed,  al- 
though some  are  normally  nearly  all  utilized.  Animal 
foods  are  better  digested  than  vegetable  foods,  with  the 
exception  of  sugars,  which  go  very  quickly  into  the  cir- 
culation. This  is  assuming  no  excess  of  meat  is  taken. 
The  protein  of  cereals,  however,  is  quite  fully  absorbed 
if  the  cereal  is  well  prepared  by  cooking.  This  is  in 
contrast  to  peas,  beans,  and  lentils  with  digestive  co- 
efficients of  only  about  80,  the  proteins  of  meat  being 
about  98  and  bread  90. 

Green  vegetables  are  more  in  the  way  of  regulators 
than  foods,  as  the  large  amount  of  waste  serves  to  ex- 
cite peristaltic  movement  in  the  intestines,  but  the  use 
of  very  large  quantities  may  be  bad  in  two  ways :  they 


FOOD  ELEMENTS  AND  FOOD  CLASSES  187 

tend  so  to  dilute  the  contents  of  the  stomach  that  the 
digestive  juices  do  not  have  full  opportunity  to  act  on 
the  important  food  elements,  and  because  of  too  active 
peristalsis  the  food  may  be  hurried  on  too  rapidly. 
One  detriment  to  an  exclusive  vegetable  diet  is  the  lack 
of  flavor,  the  presence  of  which  would  cause  better 
secretions  of  the  digestive  enzymes.  The  extractives 
or  amines  of  meat  excite  the  flow  of  gastric  juice  and 
pepsin,  which  are  needed  to  act  properly  upon  proteins. 
In  the  case  of  starchy  foods  this  is  not  necessary,  as 
they  are  not  acted  upon  in  the  stomach.  People  re- 
quiring comparatively  little  food  may  get  along  fairly 
well  on  a  vegetable  diet.  But  for  an  active  life  meat  is 
a  valuable  part  of  the  diet,  and  if  on  the  score  of 
economy  very  little  meat  is  available,  the  addition  of  the 
meat  extractives  from  bones  to  make  soup  will  excite 
the  secretions  very  well. 

One  may  eat  slightly  less  food  in  summer  than  in 
winter  on  account  of  less  necessity  of  generating  heat, 
but  the  difference  is  slight,  as  the  variation  in  weight  of 
the  clothing  and  the  heating  of  the  houses  makes  up 
some  of  the  difference.  The  chief  factor  at  all  times  is 
the  amount  of  exercise.  More  fat  should  be  taken  in 
winter  than  in  summer,  as  it  is  the  prime  heat  producer. 
It  is  astonishing  how  much  work  an  average  man  in 
good  physical  condition  can  do.  It  is  stated  that  a  hard 
day's  work  would  consist  in  raising  his  own  weight 


188  CHEMISTRY  OF  FAMILIAR  THINGS 

10,000  feet,  or  the  expenditure  of  1,400,000  foot-pounds 
of  energy.  As  the  equivalent  of  1  calorie  in  mechanical 
energy  is  3077  foot-pounds  and  a  man  gets  3000  calories 
in  his  food,  if  all  were  available  for  work  he  could  per- 
form work  to  the  extent  of  9,000,000  foot-pounds,  or 
4500  foot-tons.  As  it  is,  the  efficiency  is  about  one- 
sixth,  or  is  distinctly  more  efficient  than  a  steam  boiler, 
which  is  hardly  over  one-eighth. 

Most  foods  are  better  for  being  cooked.  If  cooking 
did  not  do  anything  else,  it  would  be  very  valuable  in 
its  effect  in  sterilizing  food  or  killing  bacteria,  moulds, 
and  even  parasites.  The  second  effect  in  its  general 
benefit  is  that  it  makes  the  food  more  palatable,  which 
is  something  of  vital  importance  in  digestion.  When 
food  is  cooked  it  is  sterilized  on  the  exterior,  but  in 
many  cases  it  is  not  heated  enough  to  sterilize  the  in- 
terior. Boasts  of  meat  are  still  rare  enough  inside  to  in- 
dicate that  the  heat  has  been  far  short  of  sterilization. 
The  writer  has  frequently  tested  bread  in  the  centre  of 
the  loaves  and  found  lactic-acid  bacteria. 

Some  foods  are  improved  in  digestibility  by  cook- 
ing, while  others  are  more  digestible  before  cooking. 
Starchy  vegetables  and  those  containing  much  cellulose 
belong  to  the  former  class.  Very  tender  meat  and  some 
vegetables  and  fruit  not  containing  starch  belong  to 
the  latter.  Meat  would  be  more  digestible  raw  if  it  were 
not  too  dense  for  satisfactory  mastication.  Some- 


FOOD  ELEMENTS  AND  FOOD  CLASSES  189 

times  meat  scraped  from  connective  tissue  is  warmed 
and  served  on  toast,  etc.,  to  invalids,  in  which  case  it  is 
most  easily  digested.  Cooking  sterilizes  the  surface  of 
meat,  which  is  the  only  part  very  likely  to  contamina- 
tion, renders  it  more  palatable,  and  in  many  cases  makes 
it  more  easily  attacked  by  the  digestive  juices  by  soften- 
ing the  connective  tissues.  Starchy  and  fibrous 
vegetables  are  made  more  digestible  and  in  most  cases 
more  palatable  by  cooking.  The  starch  granules  are 
ruptured  by  boiling  or  changed  into  soluble  dextrin 
by  dry  heat  or  into  sugar  by  moist  heat  and  acids. 
Fruits  that  especially  need  cooking  are  bananas  and 
green  apples  on  account  of  starch.  Pineapples,  roots, 
and  some  varieties  of  pears,  etc.,  need  cooking  on  ac- 
count of  cellulose.  As  nearly  all  vegetables  contain 
starch  or  woody  fibres,  practically  all  of  them  need 
cooking.  Lettuce  and  tomatoes  are  exceptions.  Celery 
has  a  good  deal  of  fibre,  but  it  does  not  seem  to  enclose 
starch,  so  boiling  it  is  optional. 

A  great  deal  of  cooking  is  carried  to  too  high  tem- 
peratures. Protein  does  not  need  212°  F.  to  become 
coagulated,  as  about  170°  F.  is  sufficient,  and  starch 
does  not  need  more  than  the  latter  temperature  to  dis- 
rupt the  granules.  Over-cooking  toughens  some  sub- 
stances, such  as  albumen.  A  great  advance  in  cooking 
has  been  brought  about  by  the  introduction  of  the  fire- 
less  cooker,  which  is  nothing  but  a  well-insulated  cas- 


190  CHEMISTRY  OF  FAMILIAR  THINGS 

ing  to  a  receptacle  which  holds  dishes  that  are  boiled  a 
short  time  only  and  the  heat  is  retained  so  as  to  complete 
the  operation  of  cooking  while  the  temperature  slowly 
falls.  The  maintenance  of  heat  is  assisted  by  contact 
with  a  vessel  of  boiling  water.  Heated  stones  or  metal 
plates, used  in  such  a  cooker,  will  give  temperatures  that 
effect  baking,  pan  broiling,  roasting,  etc. 

With  the  use  of  steamers  for  cooking,  steam  seems 
to  penetrate  more  deeply  than  water  alone  and  on  con- 
densing to  water  dissolves  the  extractives.  Where 
boiling  in  water  is  practised  it  is  best  to  plunge  the  meat 
or  vegetable  into  actively  boiling  water  and  then  merely 
cause  to  simmer.  The  surface  protein  is  coagulated  and 
acts  as  a  seal  to  prevent  excessive  extraction  of  flavor- 
ing principles.  As  little  water  as  possible  should  be 
used.  Certain  proteins  of  vegetables,  the  globulins,  are 
rendered  soluble  in  salt  water,  and,  as  most  boiling 
must  be  done  in  salt  water,  it  is  very  desirable  to  have  as 
little  water  as  possible  present. 

Baking  bread,  etc.,  is  more  of  a  chemical  operation 
than  any  other  cooking  process.  Either  carbon  dioxide 
is  formed  from  baking-powder,  which  is  a  mixture  of 
mild  and  harmless  acid  and  bicarbonate  of  soda,  or  this 
gas  is  formed  by  the  action  of  yeast  on  starch  and  mal- 
tose, as  in  bread-making,  or  else  eggs  are  beaten  up  so  as 
to  enclose  air,  as  in  cake-making.  Heat  expands  the  car- 
bon dioxide  from  the  baking-powder  or  the  air  held  by 


FOOD  ELEMENTS  AND  FOOD  CLASSES  191 

the  albumen  of  the  eggs,  until  the  coagulation  of  the 
protein  sets  the  product,  so  that  the  gas  bubbles  form 
a  spongy  consistency.  If  the  heat  drops  before  the 
protein  of  the  cake  has  coagulated,  the  cake  falls,  due 
to  the  contraction  of  the  gases,  the  original  expansion 
of  which  had  caused  the  cake  to  rise.  This  practically 
spoils  the  cake  unless  the  protein  has  not  gone  far  in 
coagulation,  in  which  case  quickly  bringing  up  the  heat 
may  cause  a  fresh  expansion. 

Pure  foods  are  those  that  are  fresh,  of  full  strength, 
and  without  substitution  of  any  kind.  The  natural 
instinct  of  mankind  has  through  ages  selected  a  wide 
range  of  animal  and  vegetable  products  which  we  now 
know  as  foods,  and,  because  of  accident  or  specially 
made  tests,  we  have  found  various  substances  to  be 
poisonous  or  deleterious  when  taken  internally.  Some 
things  are  food  when  fresh  or  when  properly  prepared, 
and  deleterious  when  stale  or  improperly  prepared. 

Many  substances  which  have  long  been  recognized 
as  pure  foods  and  are  given  the  sanction  of  the  law  on 
that  account  are  no  more  tolerated  by  many  diges- 
tions than  recently  introduced  food  preparations  which 
the  authorities,  administering  State  or  national  food 
laws,  declare  impure.  People,  however,  have  known 
them  for  so  long  that  they  are  in  a  position  to  judge  for 
themselves.  Eeference  might  be  made  to  strongly 
pickled  products  or  those  preserved  with  nitre. 


192  CHEMISTRY  OF  FAMILIAR  THINGS 

Foods  are  in  general  condemned  if  they — 

(a)  Contain  any  poisonous  ingredient. 

(b)  Are  colored  or  coated  to  conceal  inferiority. 

(c)  If  any  important  element  normally  present  is 
missing  in  whole  or  in  part. 

(d)  If  they  are  improperly  labelled. 

(e)  Are  below  standard  weight. 

(/)  Are  in  substitution  for  the  article  claimed. 

(g)  Are  stale,  decayed,  or  decomposed. 

Since  the  rigid  enforcement  of  the  pure-food  laws 
began,  say  a  dozen  years  ago,  there  has  been  a  vast 
change  in  the  quality  of  foods  sold.  At  about  that 
time  formaldehyde  and  boric  acid  were  prevalent  in 
milk;  now  they  are  practically  never  found,  but  the 
authorities  have  plenty  to  do  to  see  that  the  milk  is 
produced  properly  from  healthy  cattle  and  brought  in 
chilled  condition  to  market.  At  about  the  time  men- 
tioned salicylic  acid  and  sulphites  were  found  in  a  good 
deal  of  the  beer  sold;  wheat  or  cornstarch  in  cocoa; 
muriatic  acid  in  vinegar;  alum  in  bread;  wood  or  co- 
coanut  shells  in  spices.  A  few  years  later  the  matter  of 
benzoic  acid  in  catsup,  agar  in  ice-cream,  coal-tar  colors 
of  all  kinds  in  confectionery,  the  bleaching  of  flour 
with  nitrous  oxide  and  glucose  with  sulphur  dioxide  and 
the  treatment  of  meat  with  the  latter  were  taken  up. 
After  preventing  by  prosecution  or  discouraging  by  an 
aroused  public  opinion  hundreds  of  forms  of  gross 


FOOD  ELEMENTS  AND  FOOD  CLASSES  193 

adulterations,  it  might  be  said  that  now  the  gross  adul- 
teration of  food  is  at  an  end  in  this  country,  and  atten- 
tion is  being  focused  upon  raising  the  standards  of  food 
materials. 

Spoiled  and  decayed  food,  foods  of  low  grade, 
wormy  or  full  of  bacteria,  although  genuine,  are  now 
being  sought  after  and  removed  from  the  market.  If 
food  can  be  sold  in  sanitary  stores  where  flies  cannot 
pollute  by  their  touch  or  curious  customers  cannot 
sample  from  boxes,  bins,  or  barrels,  we  are  soon  in  a 
fair  way  towards  the  millennium  of  food  supply.  There 
should  be  one  step,  however,  taken  to  reach  this  desired 
goal  of  producing  and  supplying  food,  and  that  would 
be  to  have  standard  grades  of  cereals  and,  maybe, 
some  other  things  sold  in  less  expensive  packages. 
Rolled  oats,  farina,  rolled  and  toasted  corn  and  corn 
grits,  a  prepared  rice,  etc.,  should  be  sold  at  from  three 
or  seven  cents  per  pound  instead  of  twelve  ounces  for 
ten  to  fifteen  cents.  People  do  not  always  realize  the 
great  value  to  the  public  of  the  accurate  labelling  of 
commercial  foods.  One  can  depend  fairly  well  upon 
the  general  statements,  but  must  not  overlook  some  of 
the  fine  print. 

Alcohol  is  not,  properly  speaking,  a  food,  although 
it  gives  heat.  It  cannot  build  tissue  nor  fat;  therefore, 
the  energy  it  contains  cannot  be  stored,  but  is  given  off 

13 


194  CHEMISTRY  OF  FAMILIAR  THINGS 

as  fast  as>  generated.  Alcohol  has  physiological  action 
on  the  nerve-centres,  which  tends  to  drive  the  blood 
to  the  surface  and  thus  radiates  quickly  about  all  the 
heat  it  contributes  to  the  system,  and  is  liable  to  leave 
persons,  subject  to  exposure  a  little  after  taking  it, 
colder  than  they  were  before.  In  small  quantities  it 
aids  digestion,  but  in  large  quantities  it  retards  it.  Ac- 
cording to  Hutchinson,  any  unchanged  alcohol  in  the 
system  acts  injuriously.  Alcohol  in  excess  delays  car- 
bohydrate decomposition,  and  in  this  way  may  be  the 
cause  of  diabetes  and  by  delaying  protein  digestion  is 
liable  to  produce  a  gouty  condition.  Sometimes  only 
a  very  small  amount  of  alcohol  can  be  oxidized  without 
creating  unfavorable  effects.  Fortunately,  an  excessive 
amount  of  alcohol  gives  an  unmistakable  warning  to 
the  individual,  and  it  is  the  part  of  belated  wisdom  to 
follow  this  warning  and  refrain  from  further  partak- 
ing. The  amount  that  different  people  can  take  differs 
somewhat  with  the  individuals,  but  those  who  think 
they  can  take  relatively  large  amounts  safely  are  proba- 
bly in  most  cases  deceived,  and  quantities  that  may  be 
assumed  as  being  fairly  safe  for  daily  consumption 
should  not  be  taken  at  one  time,  any  more  than  the  total 
daily  requisite  or  permissible  amount  of  food  should  be 
taken  at  one  time.  From  one  to  one  and  a  half  fluid- 

3 "  Food  and  Dietetics,"  by  Robert  Hutchinson. 


FOOD  ELEMENTS  AND  FOOD  CLASSES  195 

ounces  of  absolute  alcohol  is  about  all  that  the  average 
adult  can  safely  assimilate  in  a  day  when  taken  at  dif- 
ferent times,  especially  after  a  meal  or  during  a  meal. 
The  following  are  the  equivalents  of  one  fluidounce : 

Brandy  or  whiskey 50  per  cent,  alcohol  2  fluidounces  or  1 

liquor-glass. 

Port  or  Sherry 20  per  cent,  alcohol  5  fluidounces  or  2% 

wine-glasses. 

Claret  or  Rhine  wines  ...  10  per  cent,  alcohol  10  fluidounces,  5 

wine-glasses  or  1 
tumbler. 

Bottled  beer 5  per  cent,  alcohol  20  fluidounces  or  1 

pint  or  2  water- 
glasses. 

When  alcoholic  liquids  are  used  as  flavoring  in  food, 
it  should  be  remembered  that  alcohol  is  volatile  with 
heat,  boiling  at  temperatures  very  much  below  that  of 
water.  When  pure,  alcohol  boils  at  173°  F.  (See  Fer- 
mentation, page  241.) 


CHAPTER  XIV 

INDIVIDUAL  FOODS 

MOST  natural  foods  are  made  up  of  all  the  important 
food  elements  in  varying  proportions,  and  so  a  classifi- 
cation is  difficult.  Meat  foods  as  a  class  are  rich  in  pro- 
tein and  fat.  Cereals  are  rich  in  protein  and  carbo- 
hydrates, but  are  lacking  in  fat.  Oils  are  liquid  fats. 
Green  vegetables  and  fruits  are  lacking  in  fat.  "When 
the  relatively  large  amount  of  water  they  contain  is 
allowed  for,  they  are  normal  foods  with  reference  to 
protein  and  carbohydrates.  Nuts  are  generally  rich  in 
protein  and  fat  but  are  lacking  in  carbohydrates. 
Mineral  matter  is  an  important  element  in  food  that  is 
found  in  all  vegetable  and  animal  products  and  is  ob- 
tained in  greater  variety  by  the  use  of  many  kinds  of 
food  rather  than  a  very  restricted  diet,  and  we  must  be 
on  our  guard  that  would-be  refinements  in  selecting  food 
do  not  reduce  the  mineral  portion  of  the  diet,  or  we 
would  suffer  as  plants  do  that  fail  to  find  sufficient 
variety  and  quantity  of  mineral  salts. 

In  food  value  oysters  are  on  a  par  with  milk,  as 
both  have  about  twelve  per  cent,  total  solids,  but  there 
is  more  protein  and  less  fat  and  carbohydrates  in 
oysters  than  in  milk.  There  has  been  some  danger  in 

196 


INDIVIDUAL  FOODS  197 

eating  oysters  that  have  been  fattened  in  fresh  water  at 
the  mouths  of  rivers  where  pollution  from  sewage  has 
taken  place,  but  the  food  authorities  have  been  watchful 
in  this  matter,  and  there  seems  to  be  little  danger  at 
present.  Many  people  demand  salt  oysters,  to  be  on 
the  safe  side.  Oysters  act  like  the  extractives  of  meat 
in  stimulating  digestion,  and  when  eaten  raw  may  im- 
part some  benefit  from  their  natural  enzymes,  as  some 
other  uncooked  foods  do,  such  as  apples  and  pine- 
apples. Oysters  get  more  food  in  the  early  spring  from 
the  diatoms  upon  which  they  live,  and  are  consequently 
fatter  and  better  than  in  the  winter.  Clams  are  con- 
sidered as  bearing  the  same  treatment  as  oysters,  ex- 
cept that  there  have  been  no  cases  of  contamination 
because  of  fattening  in  fresh  water,  as  this  procedure  is 
not  practised  with  clams. 

Lobsters,  crabs,  and  other  shell-fish  are  likely  to 
be  indigestible,  due  probably  to  the  rather  long  and 
coarse  fibres  of  their  flesh.  They  are  of  no  economic 
interest  as  food,  due  to  their  cost,  and  if  eaten  should 
be  masticated  very  thoroughly.  They  are  fairly  con- 
centrated nitrogenous  foods. 

Fish  is  a  broad  classification  and  would  have  to  be 
subdivided  to  be  treated  thoroughly.  The  most  diges- 
tible fish  are  those  in  which  the  meat  fibres  are  the  short- 
est and  the  flesh  is  freest  from  fat  or  oil.  Broiled  or 
baked  fish  are,  generally  speaking,  good  nitrogenous 


198  CHEMISTRY  OF  FAMILIAR  THINGS 

foods  and  are  believed  to  be  less  apt  to  form  uric  acid 
than  red  meat.  Due  to  its  smaller  amount  of  extractives, 
fish  is  not  as  stimulating  as  meat,  but  is  otherwise  nearly 
as  nourishing.  Canned  fish,  such  as  salmon  and  tuna, 
is  a  valuable  article  of  diet,  but  should  at  any  time  be 
discarded  if  there  is  the  least  evidence  of  spoiling. 

Eggs  are  so  well  known  that  very  little  need  be  said 
about  them.  They  have  everything  needed  to  make 
bone  and  flesh,  as  they  develop  by  heat  and  air  alone  to 
form  the  young  chicken.  They  are  too  concentrated  to 
be  taken  as  the  sole  element  of  diet,  as  the  system 
requires  waste. 

The  nutrients  of  the  egg  are  as  follows : 

Water  Proteid  Fat  Ash 

White ,,85.7  12.6  0.25  0.59 

Yolk   50.9  16.2  31.75  1.09 

The  protein  of  the  white  of  egg  is  albumen.  The 
proteins  of  the  yolk  are  known  as  vitellin  and  nuclein, 
the  latter  containing  phosphorus  of  organic  combina- 
tion. Combined  with  the  fats  of  the  yolk  are  large 
quantities  of  phosphorus-containing  substances,  which 
make  eggs  very  valuable  as  food.  The  digestibility  of 
the  egg  is  enhanced  by  beating  up  with  water,  milk,  or 
other  liquid  to  break  the  membranes  or  by  incipient 
coagulation  by  heat. 

M ilk  has  been  treated  somewhat  already  in  reference 
to  balanced  diet.  It  is  the  most  digestible  and  perfect 


INDIVIDUAL  FOODS  199 

food  we  have,  especially  when  it  is  modified  in  some  way 
for  special  requirements,  when,  if  possible,  it  is  better 
than  nature  provided.  When  milk  enters  the  stomach 
it  curdles,  and  if  it  goes  in  rapidly  it  may  form  rather 
dense  clots.  Milk  consists  of  fat,  which  is  very  per- 
fectly emulsified  by  casein  combined  with  calcium  phos- 
phate and  lactalbumin  lactose  (milk  sugar),  and  some 
mineral  matter,  in  addition  to  that  which  seems  to  be 
combined  with  the  casein.  When  the  protein  of  the 
milk  is  curdled  by  rennin,  it  carries  the  fat  with  it  and 
leaves  a  clear,  aqueous  liquid  which  is  a  solution  of 
the  lactose  and  some  of  the  salts  of  the  milk.  The  al- 
bumen serves  the  useful  purpose  of  retarding  precipita- 
tion of  casein  by  souring,  besides  assisting  in  keeping 
the  fat  in  suspension.  Analyses  of  some  different  kinds 
of  milk  of  most  general  interest  are  given  in  the  fol- 
lowing table : 1 

Total  Protein  Carbo- 

Water,  solids,  /— - — * — — >  hydrates  Fuel 

Source  of                 per  per  Albu-  Total                 (milk  value 

milk                    cent.  cent.  Casein     men  protein  Fat  sugar)  Ash  per  Ib. 

Human 87.4  12.6  1.0       1.3  2.3  3.8       6.2  0.3  319 

Cow     87.2  12.8  3.0       0.5  3.5  3.7       4.9  0.7  313 

Ewe    80.8  19.2  5.0       1.5  6.5  6.9       4.9  0.9  503 

Goat   85.7  14.3  3.2       1.1  4.3  4.8       4.4  0.8  365 

Ass    89.6  10.4  0.7       1.6  2.3  1.6       6.0  0.5  222 

Mare .91.5  8.5  1.2       0.1  0.1  1.2       5.7  6.3  180 

A  great  effort  is  now  being  made  to  improve  cow's 
milk  in  a  rational  way.  At  first  the  whole  effort  was 
directed  towards  sterilizing  milk  by  boiling  or  pas- 

1  K6nig,  "  Chemie  der  menschlichen  Nahrung-  und  Genussnaittel." 


200  CHEMISTRY  OF  FAMILIAR  THINGS 

teurizing  by  more  moderate  heating,  but  of  late  the 
efforts  have  been  directed  toward  improving  milk  at  the 
source. 

A  modern  dairy  is  kept  as  clean  as  a  human  habita- 
tion. The  stalls  are  very  simple  ones  of  galvanized 
iron,  etc.;  the  floors  are  of  cement,  with  gutters  for 
drainage,  which  are  kept  flushed,  and  the  bedding  is  re- 
newed daily.  In  one  of  the  most  modern  cow  barns  the 
writer  has  seen,  a  picture  of  which  is  shown  opposite 
this  page,  the  sides  of  the  building  are  almost  continu- 
ous panes  of  glass,  so  that  the  direct  sunlight  shines 
through  the  building.  It  is  heated  moderately  in  winter, 
so  that  it  can  be  continuously  ventilated.  The  mangers 
are  of  heavy  concrete,  which  can  be  readily  cleaned.  An 
attendant  at  this  dairy  told  the  writer  that  the  walls 
were  whitewashed  every  day,  and  that  the  cows  were 
sprayed  in  summer  time,  just  before  milking,  with  a 
wash  to  keep  the  flies  at  a  distance.  This  barn  was 
provided  with  several  porcelain  washstands  so  that  the 
milkers  could  thoroughly  clean  their  hands  with  soap 
before  milking.  Of  course,  the  udders  of  the  cows  were 
cleansed  as  well,  and,  as  milk  comes  from  the  cows  per- 
fectly sterile,  it  is  not  seriously  contaminated  when 
such  precautions  are  taken.  In  this  dairy  the  milk  when 
sold  is  found  to  contain  only  from  4000  to  11,000  bac- 
teria per  cubic  centimetre,  which  is  a  very  satisfactory 


INDIVIDUAL  FOODS  201 

showing,  considering  that  milk  allows  of  a,  very  rapid 
increase  in  bacteria.  Frequently  milking  is  effected 
with  an  automatic  apparatus,  which  is  essentially  a 
vacuum  pump  with  a  chamber  for  the  collection  of  the 
milk,  connected  by  flexible  piping  with  the  pump. 

Milk  must  be  rapidly  cooled  and  kept  cold  in  transit. 
Milk  used  to  teem  with  bacteria,  but  with  sanitary  con- 
ditions these  are  now  kept  at  a  minimum.  Limits  for 
bacteria  in  city  milk  may  now  be  set  at  about  25,000  or 
50,000  per  cubic  centimetre,  instead  of  500,000  or  1,000,- 
000,  which  a  little  while  ago  was  considered  about  as 
good  as  could  be  expected  for  milk  delivered  in  warm 
weather. 

Many  of  the  States  now  condemn  cattle  that  are 
found  to  be  tuberculous,  and  very  soon  this  will  be  gen- 
eral. Milk  is  such  a  prime  medium  for  the  growth  of 
bacteria  that  it  has  been  the  cause  of  the  spread  of  much 
disease,  particularly  typhoid,  diphtheria,  and  tubercu- 
losis, according  to  the  medical  authorities.  Everybody 
should  know  that  he  is  getting  milk  from  a  sanitary 
dairy  to  avoid  disease.  There  has  been  considerable  dis- 
cussion as  to  whether  the  pasteurizing  of  milk  improved 
it  or  was  a  detriment.  According  to  researches  made 
by  the  Department  of  Agriculture  in  Washington,  if  the 
pasteurization  is  carefully  effected, — in  other  words, 
carried  out  at  a  relatively  narrow  range  of  tempera- 


202  CHEMISTRY  OF  FAMILIAR  THINGS 

ture, — the  milk  does  not  seem  to  be  injuriously  affected ; 
albumen,  for  instance,  is  not  precipitated. 

A  few  words  might  be  said  of  the  chemistry  of 
modified  milks.  Buttermilk  is  separated  from  butter 
in  churning,  and  it  contains  more  or  less  lactic  acid 
(and,  of  course,  myriads  of  lactic  bacteria),  depend- 
ing upon  whether  or  not  the  butter  was  made  from 
soured  cream.  More  or  less  of  the  protein  of  the  milk 
has  been  rendered  soluble  by  auto-digestion  in  the  milk. 
This  and  other  soured  milks  are  more  quickly  digested 
than  ordinary  milk,  as  the  curdling  has  already  taken 
place.  It  cannot  form  dense  clots  in  the  stomach,  as 
may  happen  with  sweet  milk. 

Koumiss  is  primarily  mare's  milk  fermented  by 
means  of  yeast,  and,  as  the  action  of  yeast  on  sugar 
results  in  alcohol,  there  is  some  of  it  present.  In  this 
country  sugar  and  yeast  are  generally  added  to  cow's 
milk  and  the  fermenting  started  in  a  warm  place,  in 
bottles  with  patent  stoppers,  and  then  put  in  a  cool 
place.  The  enzymes  of  the  yeast  act  upon  the  protein 
and  peptonize  it  in  part,  so  that  it  is  very  digestible. 
For  most  purposes  slightly  skimmed  milk  is  preferable 
to  whole  milk.  Kefir  is  milk  fermented  with  kefir  fungi 
and  has  the  qualities  of  koumiss  to  a  large  degree,  but 
the  gas  which  forms  is  allowed  to  escape,  so  it  tastes  dif- 
ferently and  more  acid  is  formed  than  in  koumiss. 


INDIVIDUAL  FOODS  203 

Analyses  of  several  of  these  modified  milks  are  given 
in  the  following  table  :2 

Protein,  Sugar,  Fat,  Salts,     Alcohol,  Lactic  acid, 

percent,  percent,  percent,  percent,  percent,    percent. 

Koumiss    2.2  1.5  2.1  0.9           1.7           0.9 

Kefir     3.1  1.6  2.0  0.8          2.1           0.8 

Buttermilk    3.8  3.3  1.2  0.6            ..           0.3 

Butter  is  the  fat  of  milk  with  some  of  the  protein 
and  other  of  the  constituents  of  the  milk,  such  as  salts, 
present  in  smaller  amount.  Sweet  butter  is  made  from 
cream  that  is  not  appreciably  sour  or  acid  and  has  no 
salt  added  to  it.  Most  butter  has  had  salt  added  and 
is  colored  with  a  harmless  artificial  color  called  "butter 
yellow,"  although  it  may  have  a  very  nice  natural  yel- 
low color  in  summer.  Pure  butters  differ  from  one  an- 
other in  many  ways,  but  particularly  due  to  a  ripening 
or  fermentation  that  has  been  effected,  in  which  bacteria 
give  a  certain  flavor,  very  pleasing  in  well-made  butters. 
As  large  dairies  are  run  under  very  uniform  condi- 
tions, the  butter  acquires  some  slight  but  characteris- 
tic flavor,  due  to  the  collection  of  bacteria  that  are 
"leavened"  from  one  lot  to  another.  This  condition 
is,  however,  more  true  of  cheese,  where  the  bacterial 
flavoring  is  of  vital  importance  to  the  industry.  Butter 
is  about  the  most  nourishing  food  we  have,  as  is  shown 
in  the  table  on  page  186.  It  is  also  quite  easily  digested 
(for  a  fat),  due  probably  to  the  ease  with  which 

2  Hutchinson,  "  Food  and  the  Principles  of  Dietetics,"  third  edition, 
p.  141. 


204  CHEMISTRY  OF  FAMILIAR  THINGS 

it  is  emulsified.  Oleomargarine  is  a  wholesome  food 
for  those  who  like  it.  It  is  now  usually  uncolored,  due  to 
the  special  tax  imposed  on  colored  "oleo."  Butter  is 
preferred  uncolored  by  many  connoisseurs.  The  fats 
of  oleo  are  of  different  constitution  and  higher  melting 
point  and  it  does  not  seem  to  emulsify  as  readily  as 
butter.  If  one  can  digest  beef  fat  readily,  he  will 
find  no  trouble  with  the  digestion  of  oleomargarine, 
and  will,  in  fact,  have  less  trouble,  as  the  fats  are 
about  midway  in  consistency  between  beef  suet  and 
butter.  The  writer  gave  oleo  an  honest  trial  (for  pro- 
fessional reasons),  but  did  not  relish  it. 

Olive  oil  is  the  one  food  oil  after  milk  fat  and  butter 
that  is  most  sought  after,  and  rightly  so,  as  it  is  very 
assimilable.  One  can  depend  upon  the  labels  of  bottles 
to  disclose  the  genuineness  of  these  food  oils.  Some 
cheaper  oils  contain  carefully  refined  cotton-seed  or 
corn  oils,  which  should  be  satisfactory  substitutes  for 
olive  oil  for  the  benefit  of  those  not  caring  to  pay  for 
the  latter.  Olive  oil  is  as  concentrated  a  food  as  can  be 
found,  as  fats  give  more  heat  energy  than  proteins  or 
carbohydrates,  as  has  been  explained,  and  olive  oil  is 
nearly  100  per  cent.  fat. 

Cheese  is  a  very  valuable  and  cheap  food  when  pure, 
and  is  made  up  of  about  equal  parts  of  butter  fat  or  fat 
from  some  other  milk,  protein  of  this  milk,  water,  and 
about  four  per  cent,  of  mineral  matter.  It  is  a  very 


INDIVIDUAL  FOODS  205 

concentrated  food.  On  this  account  it  would  seem  more 
fitting  to  serve  it  at  luncheon  than  as  a  course  at  a 
full  dinner,  after  people  have  probably  already  eaten 
heartily,  unless  it  be  a  variety  of  highly-flavored 
cheese  for  the  purpose  of  stimulation  and  for  its  di- 
gestive effect. 

ANALYSIS  OF  CHEESES. 

Ratio  of  sol- 
uble to  total 
Water         Fat         Protein       Ash         nitrogen 

American  Cheddar 36.1  34.4  24.4  3.6 

English  Cheddar    35.2  30.4  27.8  3.4 

Petit  Suisse    54.6  35.0  7.3  0.6  3.2 

Camembert 53.8  22.0  17.1  4.4  86.1 

Brie   53.5  22.5  18.0  4.0  58.1 

Demi-Sel     49.6  34.0  11.8  3.0  12.2 

Hollande     42.6  20.0  23.9  5.5  22.3 

Gorgonzola 41.5  29.0  19.7  4.8  27.2 

Roquefort     36.9  29.5  20.5  7.0  47.5 

Parmesan   34.0  23.0  35.0  5.2  21.7 

In  these  analyses  plain  English  and  American 
cheeses  show  up  very  well  in  protein  and  fat.  These 
were  doubtless  made  from  whole  milk,  as  skimmed- 
milk  cheese  would  not  be  as  rich  in  fat.  These  cheeses, 
which  have  gone  through  certain  fermentative  changes, 
notably  Camembert,  Brie,  and  Roquefort,  show  a  very 
high  ratio  of  soluble  nitrogen  to  total  nitrogen  or  pro- 
tein. This  would  tend  to  make  them  more  digestible. 
But  cheeses  of  this  character  are  so  distinctive  in  flavor 
that  they  would  serve  the  purpose  of  stimulating  the 
flow  of  digestive  enzymes  more  than  any  other  purpose 
and  their  food  value  would  be  secondary.  Their  cost 


206  CHEMISTRY  OF  FAMILIAR  THINGS 

is  so  high,  in  this  country,  at  least,  that  they  would  not 
rank  high  as  foods  from  an  economic  stand-point.  Plain 
country  cheese  (low  in  fat)  is  often  found  indigestible, 
due  to  its  density,  and  must  be  masticated  thoroughly. 

MEAT  is  the  muscle  of  some  part  of  the  animal.  The 
muscles  consist  of  bundles  of  microscopic  tubes  bound 
together  with  connective  tissue,  called  collagen,  and 
this  includes  more  or  less  fat.  The  walls  of  these  tubes 
are  composed  of  elastin,  and  the  contents  of  the  tubes, 
when  the  animal  is  alive  or  has  just  been  killed,  con- 
sist of  a  syrupy  liquid,  which  is  like  the  fibrin  of  the 
blood,  in  that  it  hardens  or  clots.  When  the  animal  dies, 
this  material  clots,  and  this  causes  what  is  known  as 
rigor  mortis,  and  meat  is  not  really  fit  to  eat  until  by 
the  action  of  enzymes  this  clot  has  softened,  which  takes 
some  time,  depending  upon  the  temperature.  When  a 
chicken,  for  instance,  is  killed,  it  is  generally  kept  in  a 
cool  place  for  three  or  four  days  ' '  to  get  tender. ' '  This 
syrupy  liquid  in  the  tubes  is  composed  of  water,  pro- 
teins, meat  extractives,  and  mineral  matter.  Accord- 
ing to  J.  Konig,  pure  muscle,  freed  from  visible  fat,  has 
the  following  composition: 

Protein  18.36         Extractives    1.90 

Gelatin   1.64         Ash    1.30 

Fat    0.90         Water     75.90 

When  carving  at  the  table,  meat  should  be  cut  across 
the  grain  in  as  thin  slices  as  possible ;  not  to  give  people 


INDIVIDUAL  FOODS  207 

slim  helpings,  but  to  cut  the  microscopic  tubes  into  many 
sections  so  the  gastric  juice  can  attack  them  with  as 
much  exposed  surface  as  possible.  The  tubes  swell  up 
in  the  stomach,  the  connective  tissue  gives  way  on  being 
dissolved,  and  the  fibres  are  digested.  If  the  fibres 
are  long  and  have  not  been  cut  into  slices  in  carving, 
they  will  take  longer  to  dissolve.  The  younger  the  meat, 
the  more  tender  it  is,  but  veal  seems  to  be  an  exception, 
and  the  reason  probably  is  that  the  fibre  bundles  are 
so  loosely  held  that  they  are  torn  rather  than  cut 
through,  as  in  carving  beef  or  mutton  across  the  grain, 
and  the  stomach  juices  have  to  dissolve  the  walls  of 
the  tubes  from  the  outside  only,  instead  of  both  inside 
and  outside  at  the  same  time.  The  more  fat  in  the  tis- 
sues of  the  meat  the  slower  is  its  digestion.  As  has  been 
said  before,  the  flavor  of  the  meat  is  due  to  the  ex- 
tractives. The  red  color  is  due  to  haemoglobin,  which  con- 
tains iron.  Meat  is  most  digestible  when  lightly  cooked, 
as  it  is  soft  and  more  attackable  by  the  gastric  juice. 

Beefamdmuttonare  probably  about  equally  matched 
in  digestibility,  corresponding  cuts  being  considered. 
Ham  is  very  digestible  when  the  cutting  can  be  done  in 
thin  slices  across  the  grain,  but  when  one  comes  to  the 
stringy  ends  and  the  loose  fibres  the  meat  had  better  be 
put  through  a  chopper  to  cut  the  fibres.  Bound  of  beef 
is  much  improved  by  several  passages  through  the  mill 
or  by  pounding  to  break  the  cementing  tissues. 


208  CHEMISTRY  OF  FAMILIAR  THINGS 

Pork  is  not  only  somewhat  indigestible,  due  to  the 
fat  it  contains,  but  because  of  the  impossibility  of 
slicing  thinly  across  the  grain.  Mastication,  of  course, 
saves  work  in  the  digestive  organs. 

Game  meats  are  generally  strongly  flavored,  due  to 
the  large  amount  of  extractives.  They  seem  to  have 
this  because  of  the  violent  exercise  the  animals  take, 
especially  while  hunted  prior  to  being  killed.  Their 
muscles  break  down,  forming  amines,  and  the  animals 
die  before  the  elimination  of  this  waste. 

Chicken  and  most  fowls  have  soft  flesh,  which  is 
easily  digested,  due  to  the  short  fibres.  Analyses  of  the 
meat,  from  "Allen's  Commercial  Organic  Analysis," 
are  as  follows: 

Kind  of  meat                          Water  Fat  Ash  Protein 

White,  maximum    75.73  0.98  1.33  23.50 

White,  minimum 73.30  0.17  1.17  21.84 

Dark,  maximum 75.94  2.99  1.49  23.13 

Dark,  minimum 71.75  1.38  1.13  19.77 

Heart  and  kidneys  are  dense  and  nearly  lacking  in 
connective  tissue,  therefore  have  to  be  very  well  chewed 
to  be  digestible.  Liver  is  largely  nucleo-protein,  with 
very  little  fat  and  some  glycogen  (starch),  making  it  a 
concentrated  food. 

Sweetbreads  are  composed  of  cells  of  nucleo-pro- 
tein and  are  accepted  as  being  very  quickly  digested. 
This  is  largely  due  to  the  physical  properties  which 
seem  to  control  the  digestibility  of  almost  all  food. 


INDIVIDUAL  FOODS  209 

Tripe  is  protein,  with  a  large  percentage  of  con- 
nective tissue,  which  yields  gelatin  on  long  cooking. 

Brains  are  highly  phosphorized  cells,  composed  of 
lecithin,  etc.  According  to  recent  authorities,  brain  is 
not  well  absorbed,  and  this  highly  phosphorized  food 
is  not  specially  adapted  to  the  supplying  of  tissue  to 
the  brain  as  ordinarily  supposed. 

Horse  meat  is  much  used  abroad,  and  some  writers 
believe  it  will  be  a  standard  article  of  diet  in  this 
country  for  the  poorer  classes.  Under  government 
supervision  there  is  no  reason  why  it  should  not  be  sold, 
as  there  are  hundreds  of  thousands  of  people  in  Europe 
who  use  it  in  place  of  beef  or  mutton,  and  some  un- 
doubtedly prefer  it.  The  writer  thinks  it  would  make 
as  acceptable  a  sausage  filler  as  worn-out  cattle. 

The  varieties  of  sausage  are  too  numerous  to  men- 
tion here.  Those  which  are  practically  as  perishable 
as  ordinary  meat  are: 

A.  Fresh  pork  sausage. 
Liver  sausage. 

Smoked  sausage,  Bologna  and  Frankfurt. 

B.  Those  that  are  not  so  perishable,  as  they  are 
partially  dried,  are  known  by  various  names,  as  Cer- 
velats,  Salami,  Goteburg,  etc.     They  are  spiced  and 
treated  with  nitre. 

Cured  sausages  have  the  nourishing  properties  of 
good  meat  and  have  a  high  percentage  of  fat  in  most 

14 


210  CHEMISTRY  OF  FAMILIAR  THINGS 

cases.  The  fact  is  they  are  too  fatty  for  many  diges- 
tions, especially  the  pork  varieties. 

The  putting  of  preservatives,  bread  and  cereals, 
into  sausage  is  very  much  under  the  ban  in  the  United 
States,  and  is  little  practised.  Those  that  are  bright 
red,  such  as  Bologna,  are  treated  with  nitre,  which 
changes  the  normal  color.  Corn  meal  is  added  to 
some  pork  products  for  local  consumption,  such  as 
scrapple,  which  is  sold  largely  in  Pennsylvania,  and 
the  analysis  would  vary  with  the  amount  of  meal  used 
and  the  fat  in  the  pork. 

Tongue  is  a  good  deal  like  beef  in  composition,  but 
the  fibres  are  loosely  held  and  thin-walled,  so  it  is  easily 
masticated  and  undoubtedly  easily  digested. 

Carbo-  Fuel  value 

Water       Protein       Fat       hydrates     Ash         perlb. 

Heart,   beef    62.6  18.0  20.4  1.0  1160 

Kidneys,  beef 76.7  16.9  4.8  0.4  1.2  525 

Tongue,  beef    63.5  17.4  18.0  . .  1.1  1085 

Sweetbreads   70.9  15.4  12.1  . .  1.6  795 

Tripe     74.6  16.4  8.5  . .  0.5  665 

Liver   69.8  21.6  5.4  1.8  1.4  665 

Corned  beef  51.2  25.9  18.9  .,  4.0  1280 

VEGETABLE   FOODS. 

Peas,  beans,  and  lentils  are  of  a  class  of  vegetable 
foods  richest  in  protein  when  considered  on  a  dry  basis, 
with  the  exception  of  a  very  few  articles  that  are  not 
consumed,  however,  in  as  great  quantities,  such  as 
peanuts  and  cocoa. 


INDIVIDUAL  FOODS  211 

Cereals  are  members  of  the  family  of  grasses  and 
are  cultivated  for  their  seeds,  which  are  the  storehouses 
of  food  for  the  young  shoots.  The  nutritive  value  of  the 
cereals  ranks  quite  high,  and  they  should  constitute  the 
mainstay  of  our  diet.  They  are  about  the  most  di- 
gestible of  vegetable  food  materials,  as  regards  their 
protein,  and  are  the  chief  sources  of  starch,  which  is 
the  most  important  carbohydrate  found  in  nature. 

The  nutritive  value  of  the  proteins  of  the  different 
cereals  is  about  equal,  but  this  is  assuming  that  they 
are  softened  by  cooking  and  the  outer  protective  coat- 
ings thoroughly  disrupted.  The  cereals  are  too  low  in 
fat  to  be  perfect  foods,  but  they  are  generally  eaten  with 
butter,  cream,  or  milk,  which  improves  their  nutritive 
food  ratio.  It  will  be  seen  from  the  following  analysis 
that  oats  are  the  highest  in  fat : 


Cereal 
Oats    rolled   . 

Water 

72 

Protein 
169 

Fat 
7  3 

Carbo- 
hydrates 
66  8 

Ash 
1  9 

Calories 
perlb. 
I860 

Corn  meal  (maize)   . 
Barley  meal  

.  .    10.2 
.  .   11.9 

7.3 
10.5 

4.1 
2.2 

66.7 

72.8 

1.2 
2.6 

1550 
1640 

Rye  flour 

12.7 

7  1 

09 

78  5 

0  8 

1630 

Buckwheat  flour  .  .  . 

.    14.3 

6.1 

1  0 

772 

1  4 

1590 

Rice     

.  .    12.4 

7.8 

0.4 

79.0 

04 

1630 

Bran    

.  .    12.5 

16.4 

3.5 

61.6 

6.0 

1687 

Flour    (  roller  )    

,  .  .  12.5 

11.3 

1.1 

74.6 

0.5 

1645 

Graham  flour 

125 

11.3 

2.2 

703 

2  0 

1655 

Whole  wheat  flour  .  . 
Macaroni 

..    12.1 
.  .  .10.8 

14.2 
11.7s 

1.9 
1.6 

70.6 
72.9 

1.2 
3.0 

1660 
1640 

White  wheat  farina 

..     9.7 

11.1 

1.4 

77.6 

0.2 

1710 

3  The  author  would  think  12-14%  as  about  normal  protein  percentage 
of  macaroni.  The  table  and  most  of  the  other  analyses  in  this  chapter 
are  taken  from  "  American  Food  Materials,"  U.  S.  Dept.  of  Agric. 


212  CHEMISTRY  OF  FAMILIAR  THINGS 

Because  of  the  high  percentages  of  nutrients  in 
oatmeal,  it  is  high  in  fuel  value.  It  is  also  higher  in 
mineral  matter  than  the  other  breakfast  cereals  com- 
monly used  in  this  country.  From  what  has  been  said 
about  oatmeal,  it  does  not  leave  much  room  for  special 
commendation  of  the  other  cereals.  As  the  protein  of 
oats  does  not  form  the  strong,  glutinous  skin  that  those 
of  wheat  and  rye  do,  it  is  not  used  for  bread,  but  is  al- 
most exclusively  used  as  a  mush  or  breakfast  cereal. 
Oats  and  corn,  being  high  in  fat,  make  good  winter 
cereals,  while  wheat  and  rice  make  pleasing  summer 
dishes.  Eice  is  so  low  in  protein  and  fat  that  one 
should  always  accompany  rice  dishes  with  those  rich  in 
these  elements.  The  Japanese  eat  fish  with  the  rice. 
Oatmeal  is,  on  the  other  hand,  such  a  well-proportioned 
food  that  the  Scotch,  particularly  the  working  classes, 
are  reputed  practically  to  live  upon  it.  Macaroni  is 
made  from  flour  richest  in  gluten.  The  above  analyses 
do  not  show  as  great  a  difference  as  I  think  would  or- 
dinarily be  indicated,  and,  as  said  in  the  footnote,  a 
higher  figure  should  be  given. 

The  wheat  grain  is  composed  of  three  important 
parts :  the  endosperm  or  body  of  the  wheat,  the  germ 
or  vital  portion,  and  the  husk  or  shell.  The  endosperm 
is  composed  chiefly  of  starch,  with  the  protein  richest 
near  the  husk.  The  starch  is  nearly  free  from  protein  in 
the  centre.  The  germ  is  at  one  end  of  the  grain  and  is 


INDIVIDUAL  FOODS  213 

composed  chiefly  of  protein  and  fat  or  oil.  The  germ  is 
very  rich  in  organically  combined  phosphorus,  and  any 
germ  flours  or  flours  containing  the  germ  would  be 
valuable  on  account  of  this  organic  phosphorus  or 
lecithin,  but  the  trouble  has  been  with  the  oil  it  contains 
turning  rancid.  Some  millers  have  extracted  the  oil 
and  then  crushed  the  germ  with  the  endosperm,  but  the 
writer  feels  sure  the  lecithin  is  largely  extracted  with 
the  oil.  He  knows,  from  personal  experience,  it  is  with 
some  solvents. 

When  the  grain  is  lightly  crushed  the  germ  is  sepa- 
rated and  the  bran  removed,  while  the  balance  of  the 
grain  is  sorted  by  sifting  and  regrinding  to  obtain  or- 
dinary household  flour  and  pastry  flour.  The  latter 
is  richer  in  starch  and  so  is  desirable  for  cakes  and 
pastry  rather  than  bread,  for  which  a  high  gluten  con- 
tent is  requisite.  The  bleaching  of  flour  is  as  senseless 
an  operation  as  the  coloring  of  butter. 

The  important  different  kinds  of  flour  used  in  this 
country  are : 

Pastry  flour — rich  in  starch. 

Household  flour — rich  in  gluten. 

Whole- wheat  flour — more  phosphates  and  waste. 

Graham  flour  contains  more  bran  (needed  waste) 
and  mineral  matter  than  whole-wheat  flour.  The  par- 
ticles of  bran  in  the  so-called  whole- wheat  flour  are  finer, 
and  generally  part  of  the  bran  is  removed. 


214  CHEMISTRY  OF  FAMILIAR  THINGS 

Baking-powders  are  mixtures  of  acids  or  acid  salts, 
bicarbonate  of  soda,  and  generally  starch.  The  only 
proper  reason  for  the  use  of  starch  is  to  keep  the  par- 
ticles of  acid  away  from  those  of  the  carbonate,  as  in 
the  presence  of  even  small  amounts  of  water  they  would 
combine,  with  a  premature  evolution  of  carbon-dioxide 
gas ;  thus,  acid  +  bicarbonate  =  carbon-dioxide  gas  + 
sodium  salt  of  acid. 

Baking-powders  are  of  three  kinds,  named  from  the 
kind  of  acid  or  acid  salt  used.  Tartrate  powders  have 
tartaric  acid  or  acid  potassium  tartrate  (cream  of  tar- 
tar) ;  acid  phosphate  powders  have  an  acid  phosphate, 
such  as  those  of  lime  and  potassium;  while  alum 
powders  have,  as  acid,  principally  aluminum  sulphate. 

(a)  Acid    potassium    tartrate  -f  bicarbonate  =  sodium    potassium 

tartrate  +  C02 
(6)  Acid   potassium    phosphate  +  bicarbonate  =  potassium    sodium 

phosphate  +  COg 
(c)  Aluminum   sulphate  +  bicarbonate  =  aluminum    hydroxide  + 

sodium  sulphate  +  CC>2 

The  alum  powders  have  been  much  condemned  by 
self -constituted  authorities,  but  the  tests  conducted  by 
the  United  States  Eeferee  Board  have  demonstrated 
their  relative  harmlessness.  It  may  be  noted  that  the 
products  of  all  these  commercial  powders  are  laxatives, 
— (a)  Eochelle  salts,  (b)  alkaline  phosphate,  (c)  Glau- 
ber's salt,  while  aluminum  hydroxide  seems  to  be  inert. 

Potatoes  rank  closer  to  the  cereals  than  to  peas, 


INDIVIDUAL  FOODS  215 

beans,  and  other  vegetables,  so  far  as  composition  goes, 
although  parsnips  and  artichokes  approach  them  in 
content  of  starch.  The  sweet  potato  and  yam  are  in- 
cluded under  the  head  of  potatoes. 

The  potato  has  approximately  the  following  com- 
position : 

Carbo-  Fuel  value  per  Ib. 

Water     Protein  hydrate  Fat  Fibre  Ash        Fresh    Dry  basis 

White  ..   78.3         2.2         18.0  0.1  0.4  1.0         380         1798 

Sweet    ..   72.9         1.6         22.5  0.5  1.8  0.7         468         1723 

Yam    ...   79.6         2.2         15.3  0.5  0.9  1.5         346         1700 

Disregarding  the  water,  the  carbohydrates  are  about 
83  per  cent,  of  the  dry  weight  in  white  and  sweet  pota- 
toes. In  the  sweet  potato,  however,  there  is  sugar  as 
well  as  starch. 

Carbo-  Fuel  value 

Water  Protein  Fat  hydrates  Ash  perlb. 

Peas,  dried    10.8       24.1  1.1  61.5  2.5  1640 

Peas,  green,  edible  portion  . .   78.1        4.4  0.5  16.1  0.9  400 

Beans,  dried    13.2       22.3  1.8  59.1  3.6  1590 

Beans,  string 87.3         2.2  0.4  9.4  0.7  235 

Beans,   lima,   dried 11.1       15.9  1.8  67.1  4.1  1620 

Beans,  lima,  green 68.5         7.1  0.7  22.0  1.7  570 

Lentils    10.7       26.0  1.5  58.6  3.2  1635 

According  to  Hutchinson,  the  protein  of  legumes  is 
not  as  thoroughly  consumed  as  the  protein  of  meat  or 
even  cereals,  yet,  when  they  are  thoroughly  softened  by 
steaming  or  boiling,  the  waste  is  not  great  or  of  a  kind 
to  be  detrimental.  We  all  know  that  green  vegetables 
are  valuable  as  food,  not  so  much  for  the  nourishment 
they  provide  as  for  other  reasons.  They  generally  con- 
tain cellulose  or  allied  substances,  such  as  pectin,  which 


216  CHEMISTRY  OF  FAMILIAR  THINGS 

goes  to  waste  in  whole  or  in  large  part.  Those  veg- 
etables that  contain  both  cellulose  and  starch  should  be 
thoroughly  softened  by  cooking,  so  that  the  digestive 
juice  can  attack  the  starch,  in  spite  of  the  protective 
covering  of  cellulose  that  may  be  over  it. 

The  proteins  of  vegetables  are  globulins,  and  are 
largely  soluble  in  water,  especially  water  that  contains 
salt ;  so  the  effort  should  be  made  to  steam  them  and  to 
salt  them  before  serving,  if  possible.  When  cooked  in 
water  and  salt,  as  seems  to  be  common  practice,  there 
is  great  loss  of  food  value,  and  all  steamed  vegetables 
that  the  writer  has  tried  have  seemed  better  than  boiled, 
unless  the  cooking  water  is  made  into  a  gravy  and 
served  with  the  vegetable.  The  reason  probably  lies  in 
the  retention  of  the  globulins  and  the  nitrogenous  ex- 
tractives. Where  meat  is  part  of  the  meal  the  loss  is 
not  so  much  felt,  but  with  a  low  meat  diet  the  loss  is 
a  great  one  and  the  lack  of  extractives  or  flavor  of  the 
vegetables  is  liable  to  impair  the  digestion  by  not  stimu- 
lating the  flow  of  the  digestive  enzymes.  Some  fresh 
vegetables  and  fruits  have  enzymes  that  seem  to  have 
digestive  value.  If  we  need  the  help  of  outside  di- 
gestive juice  they  are  certainly  valuable  for  such  use. 

The  salts  of  vegetables  are  somewhat  different  from 
those  of  meat,  and  our  complex  organisms  require  them 
as  well  as  those  of  meat.  Fresh  vegetables  are  supposed 
to  have  a  laxative  effect,  but  this  lies  largely  in  the  in- 


INDIVIDUAL  FOODS  217 

fluence  of  the  waste  they  contain  and  the  water  that  one 
takes  in  this  way. 

COMPOSITION  OF  FRESH  VEGETABLES. 


Carbo- 

] 

Fuel  vah 

Water 

Protein 

Fat 

hydrates 

Ash 

perlb. 

,  ...   90.8 

1.6 

.8 

6.0 

.8 

175 

Celery    

.  ...    94.4 

1.4 

.1 

3.0 

1.1 

85 

Corn  (  sweet  )  ,  green  .  . 

...    81.3 

2.8 

1.1 

14.1 

.7 

360 

Eggplant     

.  .  .  .   92.9 

1.2 

.3 

5.1 

.5 

130 

Greens,  as  purchased 

...   82.9 

3.8 

.9 

8.9 

3.5 

275 

Lettuce   

.  ..   94.0 

1.3 

.4 

3.3 

1.0 

105 

Onions    

...   87.3 

1.7 

.4 

9.9 

.7 

235 

Pumpkins     

...   93.1 

1.0 

.1 

5.2 

.6 

120 

Rhubarb     

.  ..   94.4 

.6 

.7 

3.6 

.7 

105 

Spinach     

.  .  .   92.4 

2.1 

.5 

3.1 

1.9 

120 

Squash    , 

....  86.5 

1.6 

.6 

10.4 

.9 

245 

Tomatoes      

...   94.4 

.8 

.4 

3.9 

.5 

105 

Turnips     

.  .  .    88.9 

1.4 

.2 

8.7 

.8 

195 

Some  vegetables,  such  as  spinach  and  apples,  are 
rich  in  iron,  but  these  analyses  do  not  show  the  minor 
percentage  differences  which  may  even  be  those  of 
greatest  importance  as  food.  If  a  varied  diet  be  used, 
it  is  sure  to  include  all  that  man  requires.  The  natural 
selection  by  man,  as  dictated  by  his  instinct,  has  done 
more  than  chemistry  to  secure  what  he  most  needs. 

Fruits  in  the  fresh  state  contain,  as  a  rule,  a  very 
large  amount  of  water,  very  little  protein,  very  little 
fat,  and  more  or  less  sugar.  It  would  be  practically 
impossible  to  sustain  life  upon  them  in  any  active  pur- 
suit. They  would  be  at  best  very  bulky  foods.  Eaisins, 
figs,  dried  apples,  and  dates,  as  we  generally  get  them, 
seem  to  be  nutritious  foods,  but  this  is  more  apparent 


218  CHEMISTRY  OF  FAMILIAR  THINGS 

than  real,  for  when  swollen  again  with  water,  as  they 
would  have  to  be  for  digestion,  they  would  be  as  bulky  as 
ever.  Dates  and  figs  are  probably  the  most  nourishing 
fruits.  Green  fruits  contain  starch,  which  makes  them 
indigestible  unless  cooked.  Green  apples  are  whole- 
some when  stewed,  as  the  starch  granules  are  ruptured. 
Bananas  are  picked  green  to  send  to  northern  markets, 
and,  although  they  may  appear  ripe  when  they  become 
yellow,  they  are  nevertheless  full  of  starch  and  should 
be  cooked  for  persons  having  weak  digestions.  They 
are  fairly  nourishing  food  when  eaten  in  this  way  or 
even  raw,  if  they  can  be  digested.  Fruit  acids  of 
mature  fruit  are  claimed  by  medical  authorities  to 
stimulate  the  intestines.  They  may  also  neutralize 
some  of  the  alkali  in  the  intestines  and  lessen  the  fer- 
mentation. It  would  seem,  however,  with  a  meal  includ- 
ing green  vegetables,  that  fruit  is  not  a  requisite. 
There  are  enzymes  in  apples,  pineapples,  and  probably 
many  other  fruits  and  vegetables,  that  may  be  bene- 
ficial to  digestion  if  they  are  not  destroyed  by  cooking. 
The  enzymes  cause  the  change  of  pectin  to  pectose, 
a  form  of  sugar ;  but,  as  boiling  kills  enzymes,  it  would 
seem  to  the  writer  that  the  formation  of  jelly  in  boiling 
down  fruits  with  sugar  is  due  largely  to  the  action  of 
the  fruit  acids  upon  pectin.  When  fruits  or  their  juices 
are  exposed  to  the  air,  yeasts  come  in  contact  with  them 
and  cause  fermentation  with  the  formation  of  alcohol. 


INDIVIDUAL  FOODS 


219 


Nuts  are  very  concentrated  foods,  containing,  as  a 
rule,  a  great  deal  of  fat  and  protein.  Nuts  and  fruit 
have  been  claimed  to  form  an  ideal  food  combination 
when  taken  together,  but,  while  they  might  be  advan- 
tageous in  certain  cases,  they  would  be  too  expensive 
for  most  people  and  should  be  very  secondary  elements 
of  diet.  Nuts  are  not  easily  digested,  due  to  the  pro- 
tective influences  of  oil  and  cellulose  and  to  the  dif- 
ficulty of  thorough  mastication.  Prepared  peanuts  or 
almonds,  such  as  peanut  butter  or  almond  paste,  should 
be  more  easily  digested. 

ANALYSIS  OF  FRUITS  AND  NUTS. 


Edible  portions  Water 

Apples     82. 

Bananas   (yellow)    74.1 

Blackberries     88.9 

Cherries    88.6 

Dates,  dry    20.8 

Figs,  dry    22.5 

Grapes    78.8 

Muskmelons     89.5 

Oranges     88.3 

Peaches,  canned    93.7 

Pears     

Pineapples    89.3 

Prunes     80.2 

Raspberries    85.8 

Strawberries    90.9 

Watermelons     92.9 

Raisins    14.0 

Dried  apples 36.2 

Dried  apricots 32.4 

Chestnuts     38.5 

Peanuts  .  9.2 


Protein 
0.5 

Fat 
0.5 

Carbo- 
hydrates 
16.6 

Ash 
0.4 

Fuel  value 
perlb. 
340 

1.2 

0.8 

22.9 

1.0 

480 

0.9 

2.1 

7.5 

0.6 

245 

1.1 

0.8 

11.4 

0.6 

265 

2.2 

5.1 

70.4 

2.2 

1370 

5.1 

.  . 

70.0 

2.4 

1395 

1.3 

1.7 

17.7 

0.5 

425 

0.6 

.  . 

9.3 

0.6 

185 

0.8 

0.6 

9.7 

0.6 

220 

0.5 

0.2 

5.3 

0.3 

115 

0.6 

0.8 

14.2 

0.5 

310 

0.4 

0.3 

9.7 

0.3 

200 

0.8 

.  . 

18.5 

0.5 

360 

1.0 

.  . 

12.6 

0.6 

255 

1.0 

0.7 

6.8 

0.6 

175 

0.3 

0.1 

6.5 

0.2 

130 

2.5 

4.7 

74.7 

4.1 

1635 

1.4 

3.0 

57.0 

1.8 

1225 

2.9 

63.3 

1.4 

1230 

6.9 

8.0 

44.9 

1.7 

1300 

25.8 

38.6 

24.4 

2.0 

2560 

220  CHEMISTRY  OF  FAMILIAR  THINGS 

Bread  has  been  referred  to  on  page  184  as  a  nearly 
complete  food.  Bakers '  bread  is  fast  displacing  home- 
made bread,  because  it  can  be  made  cheaply  and  well 
by  large  establishments,  which  can  select  the  most  suit- 
able flour  and  can  and  must  keep  everything  clean  and 
sanitary.  It  seems  to  the  writer,  who  has  thoroughly 
inspected  some  very  large  bakeries,  that  bread  made  in 
this  way  is  the  most  digestible  and  appetizing  in  the 
long  run.  A  large  bakery  makes  various  kinds  of  bread, 
such  as  milk  breads,  French  and  German  Vienna,  whole- 
wheat, rye,  and  Graham  breads,  as  well  as  rolls  of  va- 
rious kinds.  Bakers  are  now  beginning  to  wrap  bread, 
which  effects  a  sanitary  improvement,  particularly  de- 
sirable for  that  which  is  handled  in  small  shops.  The 
writer  has  found  bread  purchased  in  several  small 
shops,  in  the  course  of  an  investigation  for  the  bakers, 
to  be  seriously  contaminated  in  handling.  As  disease 
has  been  reduced  by  guarding  the  water,  milk,  and  meat 
supplies,  equal  benefit  should  be  derived  by  wrapping 
bread  in  a  paper  sufficiently  pervious  to  allow  moisture 
to  escape,  and  thus  keep  the  crust  dry,  but  able  to  pre- 
vent bacteria  from  getting  at  the  bread. 

Cake  is  an  indigestible  combination  when  made  with 
a  large  amount  of  butter,  but  is,  on  the  contrary,  a 
wholesome  food,  very  nourishing  and  appetizing,  if 
made  with  the  minimum  amount  of  butter.  The  flour 
contained  is  good  food,  the  sugar  and  eggs  are  very 


o 


o 
o  0. 


51 


0 
o 


o 


) 


Drawn  by  A.  II.  Sadtler. 

Familiar  kinds  of  starch.    In  six  groups.      Viewed   horizontally  from  upper  left  to 
lower  right  corner:     rice,  wheat,  cacao,  tapioca,  corn  and  potato. 


Drawn  by  A.  H.  Sadtler. 

Mucor  mucedo.     Moulds  look  better  magnified  under  the  microscope  than  on  bread. 


INDIVIDUAL  FOODS  221 

concentrated  foods,  and  so  is  the  butter,  but  the  fat  of 
the  butter  covers  starch  grains  and,  when  cooked  with 
them,  probably  penetrates  them  so  that  the  digestive 
juices  cannot  easily  attack  either  the  fat  or  the  starch. 
Therefore,  the  amount  of  butter  used  should  be  small, 
or  else  cake  with  a  high  butter  content  should  be  eaten 
sparingly. 

Sugar  and  syrups  are  concentrated  foods.  Syrups 
rich  in  cane  sugar  do  not  seem  to  be  as  easily  digested 
as  those  rich  in  glucose.  Glucose  is  predigested  food, 
— or,  more  exactly,  starch  that  has  been  digested  with 
acid,  which  is  then  removed, — and  is  ready  for  absorp- 
tion in  the  intestines.  Cane  sugar  must  be  first  changed 
into  glucose  (dextrose)  before  its  absorption  is  possible. 
Of  course,  glucose  has  very  little  sweetness,  and  cane 
sugar  must  be  added  to  it  to  make  it  palatable,  but  pure 
refiners '  molasses  is  too  sweet  for  most  people  and  does 
not  keep  as  well  as  glucose  syrup,  unless  it  be  concen- 
trated, for  which  reason  a  combination  syrup  is  much 
used.  Maple  sugar  is  largely  cane  sugar  with  some 
natural  flavoring  from  the  maple  tree.  There  is  a  popu- 
lar feeling  that  glucose  is  deleterious,  but  this  is  not 
founded  upon  fact,  particularly  since  traces  of  impuri- 
ties, such  as  sulphur  dioxide,  at  one  time  found,  have 
been  eliminated. 

With  many  adults,  sugars  and  confectionery  can  be 
enjoyed  at  meals,  or  immediately  following  them,  while 


222  CHEMISTRY  OF  FAMILIAR  THINGS 

if  taken  at  other  times  they  become  sour  in  the  mouth 
and  cause  discomfort.  This  is  due  to  the  ease  with 
which  they  are  converted  into  acids  by  bacteria,  but 
when  there  is  gastric  juice  in  the  stomach  the  sugar  is 
protected  by  the  germicidal  effect  of  the  hydrochloric 
acid  of  the  juice  and  is  absorbed  into  the  blood  before  it 
sours.  Sugars  alone  are  not,  as  a  rule,  stimulating 
enough  to  cause  the  flow  of  gastric  juice. 

Condimental  foods  and  sauces  are  only  beneficial  by 
stimulating  the  digestion  of  other  foods.  Some  of  the 
constituents  of  spices,  such  as  cinnamic  aldehyde  of 
cinnamon  and  eugenol  of  cloves,  are  strong  antiseptics, 
and  probably  have  about  the  same  effect  on  the  system 
as  other  chemical  preservatives.  They  are  proba- 
bly harmless  in  small  quantities  and  make  food  more 
appetizing. 

Tea  and  coffee  contain  a  moderately  active  drug 
principle,  caffeine,  besides  oils  and  tannins.  Caffeine 
seems  to  act  sometimes  as  a  nerve  excitant,  but,  accord- 
ing to  medical  authorities,  more  generally  as  a  mild 
cerebral  stimulant.  Tea  and  coffee  probably  aid  di- 
gestion because  of  the  temperature  of  the  liquid. 

Cocoa  and  chocolate  rank  high  as  foods,  as  well  as 
being  mild  stimulants.  The  fat  in  cocoa  is  quite  diges- 
tible. Cocoa  is  unsweetened  chocolate,  or  the  content  of 
the  cocoa  nibs  from  which  about  half  of  the  natural  fat 
(cocoa  butter)  has  been  expressed.  So-called  Dutch 


INDIVIDUAL  FOODS  223 

cocoa  has  had  potassium  carbonate  added  to  make  it 
more  soluble.  Chocolate  is  the  same  product  contain- 
ing all  the  natural  fat  and  to  which  sugar,  vanilla,  and 
sometimes  spices  have  been  added.  Their  composition 
is  as  follows: 

Carbo-  Fuel  value 

Water  Protein      Fat     hydrate    Ash      perlb. 

Chocolate  (unsweetened)    ...10.3       12.5      47.1       26.8       3.3       2720 
Cocoa     4.6       21.6       28.9       37.7       7.2       2320 

Analyses  of  raw  and  roasted  coffees  are  here  given 
from  Allen 's  ' t  Commercial  Organic  Analysis ' ' : 

Nitrogenous 

Moisture         matter  Caffeine  Fat  Sugar  Dextrin 

Raw    10.7             12.6             1.1  11.8             7.6             0.9 

Roasted    ..     2.4             14.1             1.2  13.9             1.3             1.3 

Nitrogen-free        Crude  Total  aqueous 

Tannin,  etc.    substance  fibre  Ash  extract 

Raw 9.0  20.3  24.0  3.0  30.8 

Roasted     4.6  39.9  18.1  4.7  28.7 

Coffee  extracts  are  coming  on  the  market,  and  their 
use  will  be  prevalent  for  those  wishing  to  save  time  in 
making  coffee  and  for  campers,  etc.  They  should  con- 
sist of  nothing  but  carefully  evaporated  coffee  infusion. 
This  process  is  a  triumph  in  manufacturing  that  only 
those  who  have  tried  to  evaporate  coffee  infusion  with- 
out losing  the  aroma  can  appreciate.  The  extract  con- 
sists of  natural  sugar-like  solids  and  flavoring  oils. 


CHAPTEE  XV 

ANIMAL  FEEDING 

THE  FEEDING  of  domestic  animals  is  very  much  like 
that  of  human  beings,  as  animals  require  certain  pro- 
portions of  protein,  carbohydrates,  and  fat  for  the  best 
results.  The  difference  is  largely  that  we  must  feed  ani- 
mals efficiently  because  we  have  only  a  small  margin  of 
profit  between  what  we  expend  on  keeping  them  and 
what  we  derive  from  them  in  work  or  food  material. 
This  matter  of  feeding  used  to  be  done  by  rule-of- 
thumb,  but  now  in  large  stables,  dairies  and  even 
chicken  farms  it  is  carried  on  by  formula. 

Foodstuffs  are  sold  on  analysis,  and  a  table  of  such 
analyses  is  given  herewith. 

The  choice  of  feeding  rations  is  partly  based  on  the 
dollars-and-cents  cost  of  the  protein  and  fat  when  cal- 
culated to  the  dry  basis,  but  this  is  only  the  arithmetic 
of  the  matter ;  the  science  depends  upon  matters  harder 
to  determine.  The  United  States  Department  of 
Agriculture  has  discussed  the  matter  in  a  scientific 
and  practical  way  in  Farmers'  Bulletin  No.  346,  and 
the  writer  refers  those  specially  interested  in  the  feed- 
ing of  animals  to  this  and  similar  publications.  Only 
an  idea  of  the  subject  can  be  given  here. 

224 


ANIMAL  FEEDING 

AVERAGE  COMPOSITION  OP  FEEEDING  STUFFS.1 


225 


Feeding  stuff 

Water 

Ash 

Crude 
protein 

Carbohydrates 

Fat 
(ether 
extract) 

Crude 
fibre 

Nitro- 
gen-free 
extract 

Green  fodder  and  silage: 
Alfalfa  

Per  cent. 

71.8 
80.9 
70.8 
79.3 
74.4 
71.1 
85.7 
76.6 
61.6 

8.4 
15.3 
42.2 
40.5 
10.7 
7.7 
16.0 
11.3 
13.2 

9.2 
7.1 
9.6 

88.6 
91.2 
78.9 
88.6 
90.6 

10.9 
10.9 
15.1 
11.0 
10.5 
11.6 
10.5 

8.0 

75.7 
11.8 
8.2 

7.0 
6.8 
8.1 
8.2 
8.1 

9.2 

9.9 
10.2 
11.8 
89.9 
6.4 
11.9 
12.1 

Per  cent. 

2.7 
1.7 
2.1 
1.2 
1.5 
1.7 
2.0 
1.8 
2.1 

7.4 
6.2 
2.7 
3.4 
7.5 
6.0 
6.1 
7.2 
4.4 

5.1 
3.2 
4.2 

1.0 
1.0 
1.0 
1.2 

.8 

2.4 
1.5 
1.5 
3.0 
2.6 
1.9 
1.8 

3.4 
1.0 
4.8 
7.2 

2.0 
2.1 
1.3 
.9 
1.0 

5.7 

5.6 
5.7 
3.5 
.4 
3.3 
5.8 
3.3 

Per  cent. 

4.8 
3.1 
4.4 
1.8 
2.2 
3.1 
2.4 
2.6 
3.1 

14.3 
12.3 
4.5 
3.8 
16.6 
7.5 
7.4 
15.4 
5.9 

4.0 
3.0 
3.4 

1.1 
1.4 
2.1 
1.2 
1.3 

12.4 
10.5 
8.5 
11.8 
20.2 
10.6 
11.9 

24.1 

5.4 
28.0 
42.3 

29.2 
17.3 
23.2 
24.5 
28.3 

32.9 

35.9 
23.2 
14.7 
1.0 
10.8 
15.4 
15.6 

Per  cent. 

7.4 
5.2 
8.1 
5.0 
5.8 
9.2 
2.2 
11.6 
11.8 

25.0 
24.8 
14.3 
19.7 
20.1 
27.7 
27.2 
22.3 
29.0 

37.0 
38.9 
38.1 

1.3 
.8 
.6 
1.3 
1.2 

2.7 
2.1 
6.6 
9.5 
14.4 
1.7 
1.8 

13.0 
3.8 
6.3 
5.6 

11.0 
12.3 
6.4 
6.1 
1.1 

8.9 

8.8 
10.7 
3.3 
2.2 
19.8 
9.0 
4.6 

Per  cent. 

12.3 

8.4 
13.5 
12.2 
15.0 
14.2 
7.1 
6.8 
20.2 

42.7 
38.1 
34.7 
31.5 
42.2 
49.0 
40.6 
28.6 
45.0 

42.4 
46.6 
43.4 

7.6 
5.4 
17.3 
7.5 
5.9 

69.8 
69.6 
64.8 
59.7 
51.1 
72.5 
71.9 

44.8 
12.5 
41.9 
23.6 

39.4 
54.0 
54.7 
47.8 
50.8 

35.4 

36.8 
48.5 
63.9 
6.3 
58.4 
53.9 
60.4 

Per  cent. 

1.0 
.7 
1.1 

.5 
1.1 

.7 
.6 
.6 
1.2 

2.2 
3.3 
1.6 
1.1 
2.9 
2.1 
2.7 
5.2 
2.5 

2.3 
1.2 
1.3 

.4 
.2 
.1 
.2 
.2 

1.8 
5.4 
3.5 
5.0 
1.2 
1.7 
2.1 

6.7 
1.6 
7.2 
13.1 

11.4 
7.5 
6.3 
12.5 
10.7 

7.9 

3.0 
1.7 
2.8 
.2 
1.3 
4.0 
4.0 

Clover  —  crimson  
Clover  —  red.  . 

Corn  fodder 

Corn  silage 

Hungarian  grass  
Rape  ...    . 

Rye  fodder  
Timothy 

Hay  and  dry  coarse  fod- 
ders: 
Alfalfa  hay  

Clover  hay  —  red 

Corn  forage,  field  cured. 
Corn  stover,  field  cured. 
Cowpea  hay  

Hungarian  hay  
Oat  hay  
Soy-bean  hay 

Timothy  hay  

Straws: 
Oat  straw  

Wheat  straw  

Roots  and  tubers: 
Carrots  

Mangel-wurzels  

'  Potatoes  

Turnips      

Grains: 
Barley        

Corn  

Corn-and-cob-meal  
Oats  

Pea  meal            

Rye       

Wheat                 

By-products: 
Brewers'  grains  —  dried.  . 
Brewers'  grains  —  wet   .  . 
Buckwheat  middlings.  .  . 
Cotton-seed  meal  
Distillers'  grains  —  dried 
Principally  corn  

Principally  rye    ...    . 

Gluten  feed  —  dry  
Gluten  meal  —  Buffalo  .  . 
Gluten  meal  —  Chicago  . 
Linseed  meal  —  old  proc- 

Linseed  meal  —  newproc- 

Sugar-beet  pulp  —  fresh  . 
Sugar-beet  pulp  —  dried. 
Wheat  bran 

Wheat  middlings  

15 


i  From  Farmers'  Bulletin  No.  22,  revised  edition. 


226  CHEMISTRY  OF  FAMILIAR  THINGS 

It  is  necessary  to  have  enough  of  the  right  kind  of 
food  that  is  available  to  the  animal  and  a  certain  pro- 
portion of  waste  to  regulate  the  digestion  and  carry 
off  the  discarded  material.  Another  point  of  impor- 
tance is  that  the  food  should  be  succulent,  as  the  fresh 
plant  juices  assist  in  digestion  and  are  pleasing  to  the 
animal  as  favorite  foods  are  to  people. 

The  animal  is  treated  as  a  machine,  and  is,  in  fact,  an 
internal-combustion  engine,  and  the  food  is  calculated 
to  calories  or  therms  (1  therm  =  1000  calories  =  the 
amount  of  heat  necessary  to  raise  1000  kilogrammes  of 
water  (1°  C,).  Of  course,  all  the  fuel  value  in  grains  and 
grasses  is  not  utilized  by  the  animal,  especially  if  the 
feed  is  dried,  as  usually  is  the  case,  and  allowances  must 
be  made  for  this.  Cellulose  in  hay,  etc.,  is  only  very 
imperfectly  digested.  About  fifty  per  cent,  of  the  heat 
value  of  hay  is  utilized,  and  about  eighty  of  dry  grain. 
As  fresh  vegetable  material  is  more  digestible,  green 
corn-stalks  and  other  fresh  materials  such  as  cow-peas 
are  packed  lightly  in  towers  called  silos,  for  use  when 
fresh  pasture  or  fresh  fodder  cannot  be  had.  Air  is 
excluded  so  that  the  corn-stalks,  etc.,  remain  fairly 
fresh.  There  is  some  fermentation  (because  of  a  little 
air  unavoidably  present)  at  the  expense  of  the  sugars, 
with  production  of  carbon-dioxide  gas.  This  excludes 
oxygen,  and  then  the  alteration  is  arrested.  There  is 
less  change  in  corn-stalks  in  forming  silage  than  there 


ANIMAL  FEEDING  227 

is  in  forming  fodder  in  the  fields,  and  the  food  material 
is  more  fully  available. 

The  most  important  element  in  animal  foods  is 
protein,  due  to  its  greater  value  in  flesh  forming 
and  repairing  waste  in  tissue,  and,  as  the  only  protein 
of  value  is  the  digestible  portion,  it  is  treated  in  the  ac- 
companying table,  in  conjunction  with  the  total  energy 
value,  which  includes  all  food  elements. 

The  requirements  of  animals  for  growth  are  dif- 
ferent from  maintenance.  For  mature  animals  we  have 
two  considerations  in  feeding : 

A.  Maintenance 

B.  Milk  supply  or  labor. 

The  first  requirement  has  been  fairly  well  worked 
out  for  cattle,  horses,  etc.,  and  for  the  particular  animal 
is  based  on  the  body  weight  and  size.  It  is  particularly 
dependent  upon  the  radiating  surface  of  the  animal,  as 
the  heat  formed  from  the  food  is  radiated  from  the 
surface.  Coal  burned  in  winter  in  heating  large  cow- 
barns  is  not  lost,  as  it  is  a  cheaper  fuel  than  fodder 
silage  or  hay. 

In  addition  to  their  maintenance  animals  must  be 
fed  for  the  work  expected  of  them,  the  milk  they  are  to 
produce,  or  gain  in  weight  required,  with  steers,  etc. 

For  milk  production  an  amount  of  feed  is  given  in 
addition  to  that  required  for  maintenance,  dependent 
upon  the  amount  of  milk  the  animal  can  normally  give. 


228 


CHEMISTRY  OF  FAMILIAR  THINGS 


DRY  MATTER,  DIGESTIBLE  PROTEIN,  AND  ENERGY  VALUES 
PER  100  POUNDS. 


Feeding  stuff 


Total  dry 
matter 


Digestible 
protein 


Green  fodder  and  silage:  Pounds 

Alfalfa 28.2 

Clover — crimson 19.1 

Clover— red 29.2 

Corn  fodder green 20.7 

Corn  silage 25.6 

Hungarian  grass 28.9 

Rape 14.3 

Rye 23.4 

Timothy 38.4 

Hay  and  dry  coarse  fodders: 

Alfalfa  hay 91.6 

Clover  hay — red 84.7 

Corn  forage,  field  cured 57.8 

Corn  stover 59.5 

Cowpea  hay 89.3 

Hungarian  hay 92.3 

Oat  hay 84.0 

Soy-bean  hay 88.7 

Timothy  hay 86.8 

Straws: 

Oat  straw 90.8 

Rye  straw 92.9 

Wheat  straw 90.4 

Roots  and  tubers: 

Carrots 11.4 

Mangel-wurzels 9.1 

Potatoes 21.1 

Rutabagas 11.4 

Turnips 9.4 

Grains: 

Barley 89.1 

Corn 89.1 

Corn-and-cob  meal 84.9 

Oats 89.0 

Pea  meal 89.5 

Rye 88.4 

Wheat 89.5 

By-products: 

Brewers'  grains — dried 92.0 

Brewers'  grains — wet 24.3 

Buckwheat  middlings 88.2 

Cotton-seed  meal. 91.8 

Distillers'  grains—dried — 

Principally  corn 93.0 

Principally  rye 93.2 

Gluten  feed — dry 91.9 

Gluten  meal— Buffalo 91.8 

Gluten  meal — Chicago 90.5 

Linseed  meal — old  process 90.8 

Linseed  meal — new  process 90.1 

Malt  sprouts 89.8 

Rye  bran 88.2 

Sugar-beet  pulp — fresh 10.1 

Sugar-beet  pulp — dried 93.6 

Wheat  bran 88.1 

Wheat  middlings 84.0 


Pounds 

2.50 
2.19 
2.21 
.41 
1.21 
1.33 
2.16 
1.44 
1.04 

6.93 
5.41 
2.13 
1.80 
8.57 
3.00 
2.59 
7.68 
2.05 

1.09 
.63 
.37 

.37 
.14 
.45 
.88 
.22 

8.37 
6.79 
4.53 
8.36 
16.77 
8.12 
8.90 

19.04 

3.81 

22.34 

35.15 

21.93 
10.38 
19.95 
21.56 
33.09 
27.54 
29.26 
12.36 
11.35 
.63 
6.80 
10.21 
12.79 


About  0.05  pound  of  digestible  protein  per  pound  of 
milk  is  required.    For  horses  the  amount  of  feed  is 


ANIMAL  FEEDING 


229 


MAINTENANCE  REQUIREMENTS  OP  CATTLE  AND  HOUSES,  PER 

DAY  AND  HEAD.3 


Live 
weight 

Cattle 

Horses 

Digestible 
protein 

Energy 
value 

Digestible 
protein 

Energy 
value 

Pounds 
150 
250 
500 
750 
1,000 
1,250 
1,500 

Pounds 
0.15 
0.20 
0.30 
0.40 
0.50 
0.60 
0.65 

Therms 
1.70 
2.40 
3.80 
4.95 
6.00 
7.00 
7.90 

Pounds 
0.30 
0.40 
0.60 
0.80 
1.00 
1.20 
1.30 

Therms 
2.00 
2.80 
4.40 
5.80 
7.00 
8.15 
9.20 

based  upon  the  amount  of  work  required  or  of  which  the 
animal  is  capable.  The  following  table  will  serve  as 
an  indication  of  what  a  horse  requires  for  both  main- 
tenance and  work,  based  on  a  body  weight  of  1000 
pounds : 

REQUIREMENTS  OP  THE  WORKING  HORSE. 


Digestible 
protein  . 

Energy 
value. 

Pounds 
1  0 

Therms 
9  so 

For  medium  work  .  .  . 
For  heavy  work     .  .  . 

1.4 
2.0 

12.40 
16.00 

Having  arrived  at  a  set  of  figures  for  digestible  pro- 
tein and  therms,  it  is  necessary  to  make  trial  combina- 
tions on  paper  of  the  feed  materials  available,  taking 
into  consideration  the  protein  and  total  energy  or 
therms  in  each  as  it  comes  (with  more  or  less  natural 
moisture) . 

a  From  Farmer's  Bulletin  No.  346,  U.  S.  Department  of  Agriculture. 


CHAPTEE  XVI 

FEKMENTATION 

THE  SUBJECT  of  this  chapter  is  fermentation  in  a 
somewhat  narrowed  but  nevertheless  usual  sense  of 
alcohol  formation  from  sugars  by  means  of  yeasts. 
Nothing  very  good  is  being  said  of  alcohol  in  these  days, 
and  the  proofs  are  so  overwhelmingly  against  the  gen- 
eral use  of  alcoholic  beverages  that  it  seems  as  if  its 
prevalency  must  decline.  Many  industrial  concerns 
have  found  that  accidents  happen  more  frequently  when 
the  workmen  are  addicted  to  the  use  of  alcohol,  and  the 
general  efficiency  of  the  men  is  higher  when  alcohol  is 
not  used.  Of  course,  this  is  regrettable,  as  the  milder 
alcoholic  beverages  could  have  a  proper  place  at  the 
table  of  many  people,  who  would  not  be  harmed  by  their 
moderate  use. 

Alcoholic  fermentation  may  be  said  to  be  the  result 
of  the  ferments  called  yeast,  acting  or  feeding  on  sugars 
and  small  amounts  of  mineral  substances  and  ni- 
trogenous matter,  with  the  production  of  alcohol  and 
carbon-dioxide  gas.  This  variety  of  alcohol  is.  known 
chemically  as  ethyl  alcohol.  The  name  migl;t  be  con- 
fused with  its  near  relative  methyl  alcohol,  and  so  it  is 
frequently  called  grain  alcohol,  because  of  its  source. 

230 


FERMENTATION  231 

A  few  words  as  to  sugars  may  be  given  here,  as 
sugar  is  a  necessary  starting-point  in  fermentation. 
Cane  sugar  is  the  sweetest  of  natural  sugars.  The 
formula  of  cane  sugar  is  C12H22011.  By  taking  on  the 
elements  of  water  (H20),  on  heating  with  acids,  two 
other  sugars  are  formed  in  place  of  cane  sugar,1 — dex- 
trose and  levulose, — which  have  the  same  formula 
(C6H1206),  but  differ  nevertheless  in  some  respects, 
such  as  rotating  the  plane  of  polarized  light,  dextrose, 
as  the  name  signifies,  rotating  it  to  the  right  and 
levulose  to  the  left.  Levulose  is  sweeter  than  dextrose 
and  is  the  chief  component  of  honey.  Dextrose  is  chiefly 
found  in  commercial  glucose  (or  corn  syrup),  having 
been  made  by  the  action  of  strong  acids  on  starch.  The 
excess  of  acid  is  removed  in  purifying  the  product. 
Maltose  is  the  sugar  that  is  formed  by  the  action  of  en- 
zymes, such  as  diastase,  on  starch.  It  has  the  same 

i 

chemical  formula  as  dextrose.  Milk  sugar  or  lactose 
has  a  different  formula  from  the  other  sugars  and,  like 
most  of  them,  has  very  little  sweetening  effect.  The 
formula  is  G12E2201i .  H20,  or  cane  sugar  with  water 
of  crystallization. 

Yeast,  a  variety  of  fungus,  is  a  single-celled  plant 
and  closely  related  to  single-celled  animals.  In  fact,  it 
is  easy  to  see  how  plant  and  animal  life  may  have  sepa- 
rated. Those  organisms  that  acquired  means  of  loco- 

=  2C6H1206. 


232  CHEMISTRY  OF  FAMILIAR  THINGS 

motion,  so  as  better  to  procure  their  food  and  develop, 
entered  the  animal  "kingdom,"  and  the  others  re- 
mained vegetable.  Yeasts  grow  by  budding  or  sprout- 
ing from  the  parent  cells.  They  are  of  various  kinds, 
and  were  described  by  Pasteur  and  later  more  thor- 
oughly studied  by  Hansen,  of  Copenhagen,  who  has 
classified  about  fifty  varieties.  There  are  only  a  few 
that  are  desired  for  fermentation  with  the  production 
of  alcohol  in  beer,  ale,  and  wines,  and  these  are  Saccha- 
romyces  cerevisia  for  beer  or  liquors,  and  Saccharo- 
myces  ellipsoideus  for  wine.  There  are  others  which 
cause  unfavorable  effects  or  " diseases"  in  these  prod- 
ucts, such  as  Saccharomyces  Pastcfrianus.  So-called 
"brewers'  yeast,"  or  cerevisiae,  is  used  also  as  com- 
pressed yeast  for  bread-making.  It  used  to  be  always 
compressed  with  potato  starch,  but  can  now  be  made 
free  from  starch,  whether  moist  or  dry.  Yeasts  are  too 
small  to  be  seen  by  the  unaided  eye,  but  require  the  use 
of  a  microscope.  They  generally  grow  so  as  to  form 
a  scum  on  the  top  of  a  fermenting  liquid  or  a  deposit  at 
the  bottom. 

In  bread-making  yeast  acts  upon  a  small  percentage 
of  sugar,  that  is  in  all  cereals,  during  the  time  the  dough 
is  kept  in  a  warm  place  to  rise.  Carbon  dioxide  and  al- 
cohol are  formed  which  are  expanded  by  the  heat.  Be- 
cause of  the  elasticity  of  the  moist  gluten  and  its  setting 


FERMENTATION 


233 


in  baking,  bread  is  given  the  desired  lightness,  even 
though  the  gases  finally  escape  by  diffusion.  The  cut 
below  shows  the  optimum  temperature  for  yeast  to  be 
above  90°  F.,  but  it  is  very  active  at  a  little  below  90°  F., 
and  it  would  seem  best  to  keep  from  exceeding  that  tem- 


YCAAT.. 
LACTIC. 

ACETIC.. 


POTATO    M4*H 
CN6U3M   A£Ci 


Fio.fi. 

perature  in  the  bread-mixing  stage,  as  the  favorable 
temperature  for  the  production  of  lactic  acid  is  being 
approached,  with  its  optimum  at  110°  F.,  and  lactic  pro- 
duction must  be  avoided  in  bread-making  so  far  as 
possible.  The  lactic  bacteria  are  always  present  in  the 


234  CHEMISTRY  OF  FAMILIAR  THINGS 

air  and  consequently  in  flour.  Their  growth  is  facili- 
tated by  a  moist  dough  and  high  temperature, 

Cider  is  fermented  apple  juice,  but,  as  with  all  fruit 
juices,  yeast  does  not  have  to  be  added,  as  there  are 
myriads  of  yeast-cells  adhering  to  the  waxy  surfaces 
of  the  fruit,  and  when  pressed  they  enter  the  juice. 
Cider  should  be  made  from  whole  sound  apples,  and 
commercial  operations  for  making  cider  and  vinegar 
therefrom  are  watched  by  the  authorities,  who  can  de- 
tect the  use  of  spoiled  products  by  analyses  of  the 
finished  articles.  Cider  is  chiefly  produced  to  make 
vinegar. 

The  first  step  in  the  making  of  cider  is  the  ordinary 
fermentation  with  yeast  and  proceeds  without  access  of 
air.  The  yeast  plant  does  not  thrive  well  itself  without 
air,  but  it  produces  alcohol,  it  is  said,  better  with  air 
exclusion.  The  alcohol  fermentation  must  be  below  its 
optimum  temperature  considerably  and  should  be  about 
50°  F.  or  a  trifle  less.  It  is  best  conducted  in  cellars, 
so  that  souring  cannot  take  place.  Acid  hinders  the  al- 
coholic fermentation,  which  should  proceed  until  there 
is  about  12  per  cent,  of  alcohol  present.  Of  course,  there 
must  be  plenty  of  sugar  in  the  fruit  or  there  cannot  be  a 
full  production  of  alcohol.  After  the  alcoholic  fermen- 
tation the  liquid  is  run  over  beech-wood  chips  with  free 
access  of  air  and  at  ordinary  temperatures  so  that  acid- 
forming  bacteria  and  air  can  enter.  The  complete  f er- 


FERMENTATION  235 

mentation  takes  a  year  or  two,  but  the  acetification  takes 
place  in  from  a  few  weeks  to  as  many  months,  depend- 
ing upon  whether  or  not  the  liquid  is  agitated  or  caused 
to  flow  over  wood  shavings,  as  in  manufacturing  es- 
tablishments. The  final  change  from  alcohol  to  acid  is 
one  of  oxidation. 

C6Hi206  +  yeast  =  C2H5OH  +  2CO2 

Dextrose  Alcohol 

C2H5OH  +  02  =  CH4C02  +  H20 
Alcohol  Acetic  acid 

Besides  using  cider  for  vinegar-making,  a  fermented 
mash  of  malt  is  used.  M,alt  alone  makes  an  alcoholic 
liquid  for  malt  vinegar.  Cereal  "grits"  with  malt  are 
used,  however,  for  ordinary  distilled  vinegar,  after  dis- 
tilling the  alcoholic  liquid  from  the  fermentation  and 
acetifying. 

A  choice  vinegar  is  as  fine  an  article  as  a  choice 
wine.  The  slow  process  of  manufacture  forms  fruit 
ethers,  which  give  bouquet  to  vinegar  as  they  do  to 
wines.  A  good  vinegar  should  have  5  per  cent,  acetic 
acid  and  be  well  aged.  If  it  is  colorless  it  is  distilled 
vinegar,  which  is  used  largely  for  making  pickles,  etc., 
and  is  perfectly  wholesome  for  such  a  purpose. 

Beer  is  made  by  moderately  cooking  in  large  copper 
kettles  starchy  liquids  composed  of  malt,  generally  with 
unmalted  grain  added  to  the  malt.  Hops  are  added,  and 
then,  after  quickly  cooling,  yeast  is  introduced,  and  the 
liquid  fermented  in  wooden  vats.  Malt  supplies  the  en- 


236  CHEMISTRY  OF  FAMILIAR  THINGS 

zyme,  diastase,  to  convert  starch  of  the  malt  and  other 
added  starch  into  sugar  for  fermentation,  and  another 
enzyme  in  the  malt,  called  peptase,  changes  the  proteins 
of  the  grain  into  soluble  and  partially  digested  sub- 
stances called  peptones.  Hops  give  a  desired  flavor  and 
act  as  a  partial  preservative.  Beer  contains  about  4  to 
5  per  cent,  alcohol,  some  malt  sugar,  dextrin,  and  pro- 
tein matter  of  the  grain.  Although  it  contains  food 
elements,  it  is  more  of  a  stimulant  than  a  food.  Dark 
beers  generally  contain  more  maltose  and  there  is  some 
caramelization  of  sugars.  This  is  especially  true  of 
porters.  Beer  supplies  sugar  in  a  very  assimilable 
form,  and  the  alcohol  at  the  strength  found  is  un- 
doubtedly an  aid  in  the  digestion  of  other  food,  and  the 
carbon-dioxide  gas  present  tends  to  give  agitation  to 
the  stomach  contents.  Porter  and  brown  stouts  are 
much  used  as  tonics  for  invalids,  due  to  their  assimilable 
carbohydrates  and  alcohol  content. 

Malt  liquors  are  very  valuable  food  beverages  for 
those  who  need  them.  Beer  is  not  very  intoxicating,  but 
it  has  its  maximum  unfavorable  effect  when  taken  on  an 
empty  stomach.  In  beer-making  the  yeast  forms  at  the 
bottom,  because  the  temperature  is  held  at  about  60°  F. 
at  first,  and  later  the  beer  is  pumped  to  cool  cellars, 
which  are  about  40°  to  45°  F.,  where  the  fermentation 
progresses  more  slowly.  In  the  case  of  ales  the  temper- 


FERMENTATION  237 

ature  is  higher,  about  70°  F.,  and  the  yeast  floats  instead 
of  sinking,  as  in  beer. 

Malt  extracts  are  very  much  like  beer  except  that 
they  have  carbohydrates  which  have  not  been  converted 
into  alcohol  and  have  little,  if  any,  hops. 

Grape  juice  contains  a  great  deal  of  sugar,  which  is 
largely  dextrose  or  grape  sugar,  but  there  are  also  va- 
riable percentages  of  levulose  and  cane  sugar  present 
which  give  the  noticeable  sweetness  which  dextrose 
alone  does  not  have.  There  is  from  15  to  30  per  cent,  of 
sugar  and  minor  percentages  of  tartaric  acid,  protein, 
and  salts,  especially  potash  salts  of  tartaric  acid, 
grape  juice.  When  fermented  or  changed  into  wine, 
much  of  this  sugar  becomes  alcohol,  and  cane  sugar  is 
added  to  increase  the  alcohol  content  by  fermentation  in 
so-called  fortified  wines.  Wines  have  no  real  food  value 
unless  they  are  sweet,  in  which  case  sugar  is  added,  but 
they  have  genuine  value  in  many  cases,  as  in  the  case  of 
beer,  by  aiding  in  the  assimilation  of  other  food,  of 
course  when  taken  in  moderation.  Wines  are  always 
fermented  at  relatively  low  temperatures,  such  as  in 
cellars,  so  as  to  avoid  souring.  White  wines  are  those 
from  which  the  skins  of  the  grapes  are  separated  before 
fermentation.  Eed  wines  have  been  fermented  in  the 
presence  of  the  skins. 

Effervescing  wines  are  fermented  like  other  wines, 
but  when  bottled,  sugar  and  yeast  are  added,  which 


238  CHEMISTRY  OF  FAMILIAR  THINGS 

makes  a  second  fermentation.  After  this  has  pro- 
gressed, with  the  necks  of  the  bottles  down  to  prevent 
leakage  of  gas,  the  corks  are  dexterously  drawn — just 
enough  to  eject  the  yeast  sediment — and  then  replaced. 
This  is  done  to  clarify  the  product.  Wine  is  not  so 
highly  prized  when  first  made,  but  after  a  year  or  so 
flavoring  ethers  form  by  the  interaction  of  alcohol  and 
organic  acids,  such  as  acetic,  which  give  the  so-called 
bouquet  or  seeming  fragrance. 

Claret  is  a  natural  red  wine  from  the  Bordeaux  dis- 
trict in  France.  The  sugar  is  practically  all  changed 
into  alcohol.  The  best-known  brands  are  Medoc  and 
and  Chateau  Margaux.  A  white  sauterne  is  also  pro- 
duced in  this  and  neighboring  districts  in  France.  Sau- 
ternes  are  generally  sweeter  than  Rhine  wines.  Bur- 
gundy is  a  wine  with  more  body  than  a  claret  and  a  little 
more  sugar.  It  is  generally  red,  but  in  the  case  of 
Chablis  it  is  white.  Chambertin  is  the  best-known  red 
variety.  Hock  or  Rhine  wine  is  German  white  wine  with 
very  little  sugar. 

The  best-known  Hungarian  wine  is  Tokay,  which  is 
so  low  in  alcohol  that  it  does  not  keep  well.  It  is  very 
sweet,  being  made  from  over-ripe  grapes,  in  which  case 
the  sugar  is  at  the  maximum. 

The  table  gives  weights  of  different  ingredients  in 
100  c.c. 


FERMENTATION 
ANALYSIS  OF  IMPORTED  WINES 2 


239 


Grams 

Total 

Wine 

abso- 
lute 

Free 
fixed 

Free 
volatile 

Total 
acid 

Sugar 

Dry 

residue 

Ash 

alcohol 
in 

alcohol 

acid 

acid 

ethers 

Hock  (three  samples) 

9.73 

0.399 

0.088 

0.506 

0.062 

1.92 

0.17 

0.042 

Claret  (threesamples) 

9.68 

0.390 

0.167 

0.599 

0.243 

2.124 

0.21 

0.038 

Hungarian     wine 

(three  samples)  .  .  . 

10.16 

0.454 

0.192 

0.694 

0.077 

1.906 

0.18 

0.046 

Greek     wine     (three 

samples) 
Sherry  (threesamples) 
Madeira  (two  samples) 
Port  (three  samples)  . 

12.35 

17.80 
17.82 
18.11 

0.342 
0.286 
0.373 
0.309 

0.215 
0.161 
0.247 
0.09 

0.611 

0.487 
0.680 
0.434 

0.225 
3.015 
1.85 
2.54 

2.507 
5.06 
4.44 
5.34 

0.30 
0.50 
0.37 
0.23 

0.048 
0.061 
0.096 
0.053 

Marsala  (twosamples) 

16.8 

0.206 

0.12 

0.361 

3.50 

5.36 

0.26 

0.049 

Sherry  is  a  well-known  and  valuable  wine  from 
Spain.  It  is  fortified  by  the  addition  of  alcohol  and  has 
had  a  little  plaster  added.  It  develops  its  pleasant 
flavor  only  on  keeping.  Amontillado  and  Oloroso  are 
typical  and  standard  brands.  If  one  does  not  secure 
a  known  brand  he  is  unlikely  to  get  a  genuine,  mature, 
and  well-flavored  product,  and  imitation  sherry  is 
nearly  valueless.  Port  has  more  body  than  sherry,  is 
fortified  with  alcohol,  and  has  had  sugar  added.  Old 
port  is  very  fine,  but  immature  port  lacks  flavor  and  is 
too  sweet  for  many  people.  On  keeping,  the  added  cane 
sugar  seems  to  be  inverted  and  is  not  then  so  sweet  and 
is  more  digestible  in  the  altered  form.  Champagne  is  a 
fortified  wine  produced  in  the  province  of  Champagne, 
France.  It  is  fermented  in  the  bottles  in  addition  to 
the  primary  fermentation. 

We  come  now  to  the  strong  alcoholic  drinks.    Malt 

2  Hutchinson,  "  Food  and  Dietetics." 


240  CHEMISTRY  OF  FAMILIAR  THINGS 

beverages  contain  4  to  5  per  cent,  alcohol ;  wines,  10  to 
20  per  cent. ;  and  ardent  spirits — whiskey,  brandy,  gin, 
and  rum — contain  from  40  to  55  per  cent,  of  alcohol,  or 
by  proof  degrees  twice  these  figures,  or  80°  to  110° 
proof.  There  are  countless  liquors  and  cordials  that 
are  produced  from  flavoring  principles  and  alcohol  and 
sugar,  such  as  benedictine,  absinthe,  Curagoa,  Char- 
treuse. The  ardent  spirits  are  made  by  fermenting 
grain,  grapes,  molasses,  etc.,  with  yeasts  found  most 
suitable,  and  distilling  the  alcohol  produced  until  the 
alcoholic  content  is  right  for  the  liquor  in  question,  and 
impurities  are  eliminated.  Whiskey  is  made  from  corn 
or  rye,  sometimes  wheat.  Corn,  whiskey  is  made  either 
by  a  sour  mash  process  or  sweet  mash.  The  sour  mash 
produces  more  flavor,  due  to  the  ethers  coming  from  the 
acids  produced.  Blended  whiskeys  are  in  many  cases 
best  for  invalids,  if  the  blend  is  an  honest  one.  This  is 
due  to  the  fact  that  they  are  made  largely  from  pure 
alcohol  and  thus  comparatively  free  from  fusel  oil. 
Some  well-known  brands  the  writer  has  found  to  be 
almost  entirely  free  from  fusel  oil.  The  best  whiskey 
for  tonic  purposes  is  as  near  a  pure  dilute  alcohol  as 
can  be  found,  with  enough  flavor  to  be  pleasing. 
Whiskeys  do  not  lose  fusel  oil  on  keeping,  although  they 
become  more  pleasant,  due  probably  to  ether  formation. 
There  have  been  frequent  statements  made  that  wood 
alcohol  was  sold  as  an  impurity  or  diluent  of  ordinary 


FERMENTATION  241 

whiskey.  The  writer  has  never  seen  this  substantiated, 
and  all  cheap  suspected  whiskeys  brought  to  him  have 
been  found  free  of  wood  alcohol.  Their  rankness  has 
been  due  to  fusel  oil,  although  fusel  oil  now  is  worth 
more  than  alcohol  and  it  is  unlikely  at  present  to  be  in 
cheap  or  any  other  whiskey  in  quantity  if  the  distiller 
can  remove  it  by  fractional  distillation. 

Scotch  whiskey  is  made  from  rye,  in  stills  over  free 
fires,  and,  as  the  malt  is  impregnated  by  peat  smoke,  the 
empyreumatic  flavor  of  the  final  distillate  is  imparted. 
Pure  alcohol  is  made  in  many  cases  by  the  same  dis- 
tillers who  make  whiskey.  The  alcohol  is  part  of  the 
condensed  distillate  which  is  purest,  and  even  then  it  is 
treated  chemically  and  re-distilled  to  make  it  as  pure 
as  possible  and  to  increase  the  percentage  of  alcohol 
relative  to  water.  The  final  strength  is  about  92  to  95 
per  cent,  alcohol  by  volume.  Alcohol  can  be  made  from 
sawdust,  as  cellulose  can  be  made  into  sugar,  which  may 
then  be  fermented.  Absolute  alcohol  is  made  by  dis- 
tilling dilute  alcohol  over  lime  and  dehydrating  sub- 
stances to  remove  the  water.  Tax-free  alcohol  must 
be  denatured  or  rendered  unfit  for  drinking  by  the  ad- 
dition of  crude  wood  alcohol  and  benzol,  or  other  de- 
naturants.  A  formula  for  a  general  denaturant  is : 

Grain  alcohol    89%  per  cent,  by  volume 

Wood  alcohol 10      per  cent,  by  volume 

Benzol    %  per  cent,  by  volume 

16 


242  CHEMISTRY  OF  FAMILIAR  THINGS 

It  is  pretty  hard  to  prevent  some  workmen  from 
drinking  anything  containing  alcohol,  and  even  this 
denatured  mixture  should  be  guarded  by  manufacturing 
establishments.  Men  have  been  known  to  drink  shellac 
mixed  with  alcohol,  and  other  most  surprising  combina- 
tions with  alcohol  and  even  gasolene. 

Brandy  is  a  distillate  from  wine.  The  best  brandies 
have  always  been  made  from  French  wines,  and  unless 
one  knows  of  a  good  domestic  grade  it  would  be  well  to 
purchase  the  best  known  French  cognac  (brandy). 
Judging  from  their  composition  alone  it  would  seem  as 
if  brandy  ought  to  serve  every  medicinal  purpose  that 
whiskey  would,  and  rather  better,  in  fact,  due  to  its 
greater  freedom  from  matters  other  than  alcohol,  water, 
and  flavoring  ethers. 

Distillates  from  other  fermented  fruit  juices  than 
grapes  are  known  by  the  names  of  the  fruits,  such  as 
apple  brandy,  peach  brandy,  etc.  They  should  contain 
40  to  50  per  cent,  of  alcohol,  and  are  flavored  with  fruit 
ethers.  The  labels  must  set  forth  the  actual  source  in 
accordance  with  the  pure-food  laws. 

Rum  is  a  distillate  from  fermented  molasses,  and  gin 
is  a  grain  spirit  given  a  special  aroma  by  the  addition  of 
juniper  berries  on  distillation. 

Milks  rich  in  sugar,  such  as  mare's  milk,  may  be 
fermented  with  compressed  or  special  yeasts,  such  as 
kefir  grains.  As  mare's  milk  is  not  used  much  in  this 


FERMENTATION  243 

country,  except  as  nature  intended,  it  is  customary  to 
add  sugar  to  cow's  niilk  for  making  mildly  alcoholic 
beverages.  Koumiss,  Jcefir,  and  other  preparations  are 
made  in  this  way.  Koumiss  contains  not  only  alcohol, 
carbon  dioxide,  and  lactic  acid,  but  the  protein  is  gen- 
erally partially  digested  to  albumoses  or  peptones. 
These  drinks  are  not  only  stimulating  like  other  weak 
alcoholic  beverages,  but  are  very  rich  in  nutrients. 
They  could  be  more  used  to  advantage.  In  Philadelphia 
and  doubtless  in  many  other  places  they  are  made 
regularly  by  the  larger  milk  dealers  and  delivered  to 
customers. 


CHAPTEB  XVII 

CHEMISTRY  OF  THE  BODY 

WE  SEE  in  various  ways  that  matter  and  force  are 
indestructible.  A  plant  may  have  a  beautiful  flower 
which  withers  and  in  the  course  of  nature  falls  to  the 
ground.  It  decomposes  largely  into  carbon  dioxide  and 
water  vapor,  which  help  to  nourish  new  plant  life.  The 
nitrogen  is  converted  into  nitrate  by  bacteria  of  the 
soil,  and  the  mineral  it  contains  assists  in  forming  new 
plant  growth. 

The  heat  of  the  sun  causes  the  carbon  dioxide,  al- 
ways in  the  air,  to  combine  with  water  in  the  plant 
tissues  to  produce  formaldehyde,  which  is  induced 
within  the  plant  to  form  sugar.1  The  sugar  is  changed  to 
starch  by  plant  ferments  (enzymes)  and  is  used  to  sup- 
port animal  life.  Sooner  or  later  all  animal  matter  re- 
turns to  its  elements,  —  to  the  air  or  soil  as  food  for  new 
plant  life,  —  and  the  endless  chains  of  plant-to-plant  or 
plant-to-animal-to-plant  are  perpetuated. 

We  have  just  referred  to  the  ferment  or  enzyme 
action  which  occurs  in  the  green  parts  of  plants.  This 


=       CH2o        +     o2 

Carbon  dioxide  Water  in  presence  of  Formaldehyde  Oxygen 

chlorophyll 

6CH20         =  C6Hi206 

Formaldehyde  Dextrose  (sugar) 

244 


CHEMISTRY  OF  THE  BODY  245 

enzyme  action  is  one  of  the  most  important  classes  of 
actions  that  take  place  in  plant  and  animal  changes. 
When  man  wants  to  carry  on  a  chemical  change  he  can 
resort  to  drastic  means,  such  as  great  heat,  electricity, 
or  the  use  of  the  most  powerful  acids  or  alkalies.  Not 
so,  however,  in  nature.  The  body  heat  is  only  98.6° 
Fahrenheit  (38°  Centigrade),  and  plant  temperatures 
are  generally  below  this.  Nature,  therefore,  had  to 
find  some  way  of  energizing  the  chemicals  she  used,  and 
the  wonderfully  perfect  system  of  the  use  of  ferments 
or  enzymes  materialized. 

We  would  have  great  difficulty  in  causing  water 
and  carbon  dioxide  to  unite  to  form  formaldehyde  and 
to  condense  this  to  make  sugar.  Outside  of  animal  or- 
ganisms we  find  sugars,  starch,  and  protein  substance  to 
be  fairly  stable  as  regards  oxidation,  but  in  our  bodies 
they  are  consumed  regularly  to  produce  heat  and  mo- 
tion. 

Some  of  the  most  important  enzymes  in  plants  are 
those  that  cause  the  action  just  referred  to, — namely, 
the  change  of  sugar  into  starch  or  of  starch  into  sugar, 
as  when,  by  the  influence  of  the  enzyme  (diastase),  the 
starch  in  germinating  barley  is  changed  to  a  variety  of 
sugar  forming  the  first  tissues  of  the  new  plant.  In  ani- 
mals there  are  enzymes  similar  to  those  in  plants  and 
still  other  enzymes  for  different  purposes.  Sugar  (dex- 
trose) is  changed  by  an  enzyme  in  the  liver  to  a  starch 


246  CHEMISTRY  OF  FAMILIAR  THINGS 

(glycogen),  and  this  in  turn,  when  it  goes  into  the  blood, 
is  changed  by  another  enzyme  back  again  to  dextrose, 
in  which  form  it  is  used  in  the  cells  to  give  heat.  En- 
zyme action  then  probably  comes  into  play  again,  and 
the  dextrose  is  converted,  finally,  into  practically  the 
same  carbon  dioxide  and  water  vapor  that  existed  when 
it  was  taken  up  by  the  plants.  The  transformation  is  in 
the  muscle  cells  and  creates  heat.2 

We  know  that  the  lean  flesh  of  our  bodies  (as  with 
other  animals)  is  protein.  The  fat  is  much  like  other 
animal  fats.  Chemists  have  analyzed  it,  but  the  writer 
will  not  quote  the  results  of  those  investigations,  as  it 
is  of  no  great  importance  here.  The  bones  are  in  part 
inorganic  and  in  part  of  organic  substance.  The  inor- 
ganic matter  is  chiefly  calcium  (lime)  phosphate.  The  or- 
ganic matter  is  chondrin,  which  forms  gelatin  on  boiling. 
In  old  persons  the  bones  have  too  much  mineral  matter 
and  too  little  of  the  chondrin.  This  is  probably  a 
matter  of  the  circulation  rather  than  excess  of  lime  in 
the  food.  The  result  is  brittleness  in  the  bones  of  their 
bodies. 

The  outer  layer  of  the  skin  is  composed  of  altered 
protein  matter  (protoplasm  of  the  cells)  and  is  a  tough- 
ened tissue  as  compared  with  ordinary  proteins.  The 
skin  is  designed  to  endure  considerable  mechanical 

2C6Hi206    +      602      =  6C02  +    6H20 

Dextrose  Oxygen  Carbon  dioxide  Water 


CHEMISTRY  OF  THE  BODY  247 

abuse,  such  as  abrasion,  and  it  is  a  heat  insulating  sub- 
stance. When  the  toughening  process  is  carried  a 
little  further,  we  have  the  tissues  of  the  'hair  and  nails. 
These  tissues  are  called  keratin.  We  all  know  from  our 
senses  about  how  much  heat  and  cold  they  can  stand. 
These  tissues  all  stand  acids  better  than  alkalies.  Mild 
acids  such  as  vinegar  do  not  seem  to  affect  the  skin,  hair, 
or  nails  at  all,  but  alkalies  such  as  ammonia  or  sodium 
hydroxide  attack  them,  and,  if  concentrated,  quickly  dis- 
solve the  thin  layers  of  the  skin.  They  also  swell  and 
would,  in  time,  dissolve  the  hair  or  nails.  Mild  alkalies 
such  as  borax,  especially  when  diluted  in  soap,  do  not 
have  much,  if  any,  unfavorable  effect. 

The  perspiration  that  exudes  through  the  skin  con- 
tains, besides  water  (which  constitutes  all  but  about 
twelve  parts  per  thousand),  fats,  acids,  and,  normally, 
a  little  urea.  There  is  a  little  respiration  through  the 
skin,  and,  though  only  a  small  amount  of  the  exchange 
of  oxygen  for  carbon  dioxide  takes  place  through  the 
skin,  this  minor  amount  is  probably  very  necessary  for 
some  reason,  and  therefore  the  pores  should  be  kept 
open,  as  the  solid  matter  of  the  perspiration,  especially 
fat,  condenses  there. 

As  the  blood  is  our  vital  fluid,  which  is  continually  re- 
making practically  all  our  tissues,  we  should  consider  its 
composition.  It  is  composed  of  water  which  has  in  solu- 
tion protein  material,  known  as  fibrinogen,  seroglobu- 


248  CHEMISTRY  OF  FAMILIAR  THINGS 

lin  and  seralbumin,  and  saline  matter ;  and  suspended  in 
this  solution  are  red  and  white  corpuscles.  The  blood  is 
normally  alkaline.  It  seems  that  neutral  salts  which  we 
must  take  in  food  are  split  into  components,  acid  and 
alkaline.  The  acid  (hydrochloric  from  common  salt) 
gives  the  acid  content  to  the  gastric  juice,  and  the  alka- 
line elements  go  into  the  blood.  Fibrinogen  is  changed 
into  insoluble  fibrin  when  the  blood  clots.  Dextrose  is 
always  present  in  the  blood  to  the  extent  of  about  0.1  per 
cent.  The  red  corpuscles  contain  an  enzyme  that  acts 
like  the  chlorophyll  of  plants  in  causing  some  of  the 
most  fundamental  changes  in  the  animal  organism. 
This  enzyme  contains  iron  and  is  known  as  hcemoglobin. 
When  it  takes  up  oxygen  in  the  lungs  it  is  known  as  oxy- 
haemoglobin.  This  oxygen  is  then  given  up  in  the 
tissues  to  oxidize  them,  creating  heat  and  energy.  The 
white  corpuscles  or  leucocytes  are  protoplasmic  cells 
like  amoebae  and  can  take  up  and  digest  foreign  organic 
impurities,  such  as  bacteria,  in  the  same  way  as  amcebae 
absorb  foreign  matter,  thus  purifying  the  blood. 

A  very  important  substance  in  our  bodies  is  lecithin, 
a  phosphorus-containing  substance,  which  seems  to  be 
the  very  germ  or  centre  of  the  cell  activities  and  is  es- 
pecially important  as  a  constituent  of  the  brain  and 
nerve  centres.  But,  while  it  is  so  important,  well-se- 
lected food  ordinarily  contains  sufficient  amounts  of  this 


CHEMISTRY  OF  THE  BODY  249 

substance,  and  it  is  not  necessary  except  for  invalids  in 
very  special  cases  to  select  food  rich  in  phosphorus. 

In  respiration  carbon  dioxide  is  given  off  by  the 
blood  in  the  lungs.  The  alkaline  condition  of  the 
blood  enables  it  to  carry  the  carbon  dioxide  from  the 
spent  tissues.  When  the  blood  is  full  of  carbon  dioxide 
it  contains  bicarbonate,  which  breaks  3  down  into  car- 
bonate in  the  lungs  and  thus  carbon  dioxide  is  given  off. 

The  importance  of  the  alkaline  condition  of  the 
blood  is  thus  shown,  and  it  can  be  seen  how  necessary 
moderate  quantities  of  salts  are  in  the  food,  as  the  acid 
radicle  aids  digestion  in  the  stomach,  and  the  alkali- 
forming  portion  is  required  for  carrying  carbon  dioxide 
in  the  blood.4 

The  substance  of  the  teeth  differs  from  the  bones  in 
the  proportion  of  organic  matter,  in  the  density  of 
its  structure,  and  in  containing  a  more  acid-resisting 
mineral  matter,  called  calcium  fluoride.  The  mouth 
secretions  normally  contain  alkali,  which  tends  to  pro- 
tect the  teeth,  and  if  they  were  kept  perfectly  free  from 
adhering  food  remnants  and  bacterial  deposits  the  teeth 
would  not  be  very  apt  to  decay.  But  starchy  food  be- 
tween the  teeth  is  apt  to  undergo  lactic-acid  fermenta- 


82NaHCQ3          =  NaaCOs  +  C02  +      HaO 

Sodium  bicarbonate  Sodium  carbonate  Carbon  dioxide  Water 

*2NaCl  +        H2O         +       CO2      =     NaaCO3     +  2HC1 

Salt  Water  Carbon  Sodium  Hydrochloric 

dioxide  carbonate  acid 

(in  blood)  (in  stomach) 


250  CHEMISTRY  OF  FAMILIAR  THINGS 

tion,  and  the  generation  of  this  strong  acid  in  direct  con- 
tact with  the  teeth  attacks  the  enamel  (the  hard  outside 
coat)  and  then  the  softer  dentine  underneath  is  likely 
to  decay. 

As  practically  all  the  agencies  of  dental  decay  come 
from  bacteria  in  the  mouth  and  throat,  it  would  seem  as 
if  a  very  good  plan  would  be  to  disinfect  the  mouth,  es- 
pecially after  cleaning  the  teeth  preparatory  to  going 
to  bed,  as  then  the  fluids  of  the  mouth  stop  flowing. 
Bacterial  activity  is  also  greater,  due  to  the  long  period 
of  action  allowed  it.  There  are  several  safe  disinfect- 
ing washes  that  are  efficient  and  some  that  are  ineffi- 
cient. Diluted  hydrogen  peroxide  and  phenol  sodique 
are  certainly  efficient  and  safe.  Physicians  and  dentists 
are,  of  course,  able  to  prescribe  others  that  may  be  more 
agreeable  and  as  efficacious. 

In  addition  to  treating  of  the  chemistry  of  the  body 
tissues,  this  chapter  is  designed  to  show  the  influence 
of  chemistry  upon  one's  health.  One  of  the  most  im- 
portant influences  the  chemist  has  had  in  relation  to 
health  is  his  discovery  of  remedial  chemicals,  chiefly 
synthetic,  or  built-up  substances,  and  in  the  antiseptic 
preparations.  Important  as  it  may  be,  however,  this 
article  will  not  treat  of  remedial  agents  that  the  chemist 
has  supplied  to  the  physician. 

The  health  of  the  individual  is  governed  largely  by 
considerations  other  than  the  use  of  drugs  and  chemi- 


CHEMISTRY  OF  THE  BODY  251 

cals.  This  must  not  be  taken  as  underrating  the  physi- 
cian, as  he  is  expected  to  serve  when  natural  agencies 
fail.  Natural  influences  contributing  to  health  are: 
Cheerfulness,  exercise,  fresh  air,  sunlight,  cleanliness, 
pure  water,  and  pure  food.  The  assertion  that  chemis- 
try plays  a  part  in  all  these  categories  might  be  dis- 
puted. It  would  be  generally  admitted  that  chemistry 
plays  some  part  in  a  consideration  of  the  purity  of 
water  and  food,  for  instance,  but  as  to  cheerfulness  and 
exercise  it  might  be  asked,  How  can  they  have  anything 
to  do  with  chemistry?  The  living  body  is  a  laboratory 
in  which  an  innumerable  number  of  chemical  changes 
are  continually  taking  place,  and,  just  as  in  a  highly  or- 
ganized manufacturing  laboratory,  when  orders  are  not 
given  or  miscarry,  processes  will  go  wrong  and  much 
damage  to  the  products  and  even  to  the  plant  may  re- 
sult, similarly  in  the  body,  if  the  person  is  nervously  ex- 
cited when  food  should  be  digesting  or  if  he  is  unhappy, 
the  system  transmitting  orders  through  the  nerves  is 
impaired  and  sufficient  blood  is  not  sent  to  parts  requir- 
ing it,  and  so  the  chemical  reactions  do  not  take  place 
properly.  It  is  impossible  to  make  chemicals  or  find 
drugs  outside  of  the  body  that  will  keep  the  body  healthy 
or  vigorous,  as  is  the  natural  tendency.  The  digestion 
of  food,  as  we  have  seen,  is  effected  by  ferments  or  en- 
zymes produced  in  the  system.  Of  these  substances, 
ptyalin,  pepsin  and  pancreatin  are  examples.  Normally 


252  CHEMISTRY  OF  FAMILIAR  THINGS 

they  are  supplied  in  proper  quantities,  but  when  the 
nervous  system  is  deranged  they  are  not  produced 
or  distributed  properly  and  trouble  ensues. 

Exercise  is  not  ordinarily  treated  in  chemical  text- 
books, but  is  brought  in  here  of  necessity.  Consider 
again  a  chemical  works.  Most  readers  may  never  have 
seen  one  except  from  the  outside,  but  what  is  here  said 
of  them  will  probably  be  credited.  An  important  con- 
sideration is  often  that  of  agitation  or  stirring  up  a 
liquid  during  a  chemical  reaction.  When  soap  is  made, 
the  fat  and  lye  are  agitated  by  boiling  so  that  the  two 
layers  may  soon  blend  and  form  soap.  When  butter  is 
being  made,  the  cream  must  be  churned ;  the  ingredients 
of  bread  must  be  kneaded  or  thoroughly  mixed ;  vinegar 
is  made  in  factories  very  much  quicker  than  in  the  home 
by  dripping  the  cider  or  malt  extract,  etc.,  over  wood 
chips  instead  of  letting  it  remain  without  agitation; 
similarly,  the  chemical  reactions  in  the  body  do  not 
work  quickly  enough  or  efficiently  without  agitation. 
The  reactions  not  only  take  place  better  when  the 
vessels,  such  as  the  stomach,  are  shaken,  but  waste  is 
more  perfectly  eliminated.  Another  benefit  of  exercise 
is  that  it  promotes  better  breathing. 

Direct  sunlight  has  two  known  effects.  It  is  a  power- 
ful germicide,  being  especially  fatal  to  organisms  that 
are  the  causes  of  most  human  diseases.  These  or- 
ganisms are  known  as  anaerobic  bacteria,  because  they 


CHEMISTRY  OF  THE  BODY  253 

do  not  require  air  to  live.  Strong  light  is  inhibitive  to 
their  activities.  If  it  were  not  for  the  germicidal  effect 
of  the  sunlight  the  human  race  might  soon  be  extinct, 
due  to  dangerous  bacteria  abounding  in  the  open  air, 
whence  they  might  be  carried  by  the  breezes  from  places 
of  sickness  to  widely  separated  homes  and  places  of 
congregation.  The  chemical  action  of  the  sunlight  is 
probably  due  to  the  ultra-violet  rays  and  ozone  formed 
by  them,  and  possibly  other  influences  not  at  present 
considered ;  but  the  active  effects  are  certain,  as  will  be 
noted  by  the  way  many  colors  fade  in  the  light.  This 
was  particularly  noticeable  before  the  chemist  helped 
the  dye-color  manufacturer  to  know  the  classes  of 
colors  that  would  best  resist  the  action  of  light.  Besides 
the  germicidal  effect,  the  sunlight  is  stimulating.  Note 
the  way  it  draws  the  blood  to  the  surface  and  thus  stim- 
ulates the  circulation. 

The  role  of  chemistry  is  apparent  in  promoting 
health  in  other  ways,  such  as  in  the  matter  of  cleanli- 
ness. People  are  not  nowadays  likely  to  be  well  unless 
they  are  clean.  Savages  are  not  as  resistant  to  diseases 
to  which  they  are  subject  as  enlightened  people;  but 
even  if  they  could  keep  well  without  cleanliness  they 
live  in  the  open,  a  situation  naturally  conducive  to 
health.  Dirt  hides  and  protects  bacteria,  which  are  the 
direct  causes  of  most,  if  not  all,  diseases.  Chemistry  has 
aided  cleanliness  and  the  preservation  of  health  by  its 


254  CHEMISTRY  OF  FAMILIAR  THINGS 

contribution  of  ammonia,  alkali,  soda,  borax,  etc.,  anti- 
septics and  synthetic  remedies. 

It  would  be  very  interesting  for  the  bacteriologist 
to  investigate  the  bacterial  contents  of  the  dirt  con- 
tainer of  a  vacuum  cleaner,  used  in  the  home  or  public 
meeting-place.  The  microscope  will  show  where  the 
worn-out  particles  of  clothing,  carpets,  and  shoes  have 
gone,  and  how  much  street  dirt,  organic  and  inorganic, 
has  come  into  the  houses,  only  to  be  promptly  removed 
and  burned  or  used  to  fertilize  the  garden  by  shallow 
burial  where  the  corn  or  lima  beans  are  cultivated. 

Natural  water  contains  small  amounts  of  salts,  such 
as  lime  and  magnesia.  In  addition  to  mineral  matter, 
there  are  nearly  always  some  organic  materials  and 
bacteria.  People  generally  have  to  drink  the  local  water 
supply,  but  if  credible  authorities  question  its  purity,  it 
should  be  boiled,  or  else  treated  water  should  be  used, 
so  as  to  avoid  the  bacteria.  Very  few  bacteria  in  water 
are  harmful ;  the  only  one  of  prominence  is  the  typhoid 
bacillus,  as  is  shown  in  Chapter  VII.  As  to  treated 
waters,  there  are : 

1.  Waters  from  large  (or  sometimes  small)  sand 
filters. 

2.  Water  that  has  been  boiled. 

3.  Ozonized  water. 

4.  Distilled  water. 


CHEMISTRY  OF  THE  BODY  255 

5.  Water  treated  with  a  little  ordinary  bleaching 
powder. 

6.  Water  treated  with  ultra-violet  light. 

Any  one  of  these  methods  of  purification  may  be 
good  under  certain  circumstances.  It  is  very  satisfac- 
tory, if  it  can  be  done,  to  have  your  own  purifier,  such 
as  a  distilling  apparatus  or  an  electric  ozonizer. 

In  a  previous  chapter  the  subject  of  food  was  treated 
in  detail.  To  those  who  are  normally  vigorous  the 
composition  of  the  food  is  probably  of  minor  influence 
upon  the  health.  The  human  being  is  a  wonderfully 
efficient  furnace  which  does  not  need  as  much  fuel  as  is 
generally  supplied,  and  the  amount  of  certain  elements 
can  be  varied  and  yet  be  efficient.  The  afore-mentioned, 
often  neglected,  influences  are  so  potent  as  to  make  the 
food  itself  almost  a  minor  consideration.  One  reason 
of  this  is  that  if  other  conditions  are  not  favorable  good 
food  may  become  a  violent  poison  in  the  system,  due  to 
nervous  strain  or  overtaxation  of  the  digestive  organs. 

Eeference  has  been  made  to  the  service  chemistry 
has  performed  in  supplying  antiseptic  preparations  for 
medicinal  and  household  use.  The  words  antiseptic  and 
disinfectant  have  somewhat  the  same  significance. 
Septic  means  putrefying,  so  that  an  antiseptic  is  some- 
thing that  opposes  or  prevents  putrefaction,  or  bacterial 
growth.  A  disinfectant,  strictly  speaking,  is  something 
used  to  check  the  spread  of  a  contagious  disease.  Anti- 


256  CHEMISTRY  OF  FAMILIAR  THINGS 

septic  is  the  broader  term  and  the  one  I  will  use  in  this 
section.  The  following  is  a  list  of  the  more  frequently 
used  antiseptics.  One  of  the  very  best  known,  namely, 
mercuric  chloride  (corrosive  sublimate),  because  of  its 
very  poisonous  properties  should  be  used  only  by  ad- 
vice of  physicians. 

Ozone  Salicylic  acid 

Mercuric  chloride  Wintergreen  oil 

Iodine  water  Benzoic  acid 

Bromine  water  Phenol  (carbolic  acid) 

Potassium  permanganate  Boric  acid 

Thymol  Hydrogen  dioxide 

Bleaching  powder  Sulphur  dioxide   (burning  sulphur) 

Eucalyptol  Alcohol 

Camphor  oil  Glycerin 

Sassafras  oil  Copperas 

Formaldehyde   (formalin)  Zinc  chloride 

Oils  of  sassafras  and  wintergreen  are  two  of  the  best 
preservatives  for  commercial  use,  such  as  for  starch  or 
flour  paste.  Safrol  is  the  active  agent  in  the  former 
and  methyl  salicylate  in  the  latter.  Some  of  these  sub- 
stances will  be  referred  to  elsewhere  in  this  book. 
Bleaching  powder  is  used  for  disinfecting  outhouses 
and  cellars,  and  is  very  efficient.  It  is  effective  in 
quantities  as  small  as  1  to  2  parts  per  million  in  purify- 
ing drinking  water  for  towns  and  cities.  Formal- 
dehyde is  of  the  most  general  use  for  disinfecting 
rooms  and  clothing  after  sickness.  There  are  va- 
rious ways  of  using  it.  Probably  the  best  way  is  to  use 
a  special  lamp  and  vaporize  tablets  of  para-formalde- 
hyde by  heating,  which  causes  the  liberation  of  formal- 


CHEMISTRY  OF  THE  BODY  257 

dehyde  gas.  Formaldehyde  is  effective  when  sprayed 
with  water  and  a  little  glycerin.  About  five  ounces 
each  of  formalin  and  glycerin  are  used  in  a  gallon  of 
water  in  this  way.  As  a  mild  preventive  it  is  diluted 
with  three  volumes  of  water  and  filled  into  saucers,  and 
pieces  of  cloth  are  partly  immersed  to  act  as  wicks  and 
assist  in  vaporization.  Sulphur  is  often  burned  and  the 
heat  of  its  combustion  is  used  to  vaporize  formaldehyde. 

Hydrogen  peroxide,  as  is  well  known,  is  not  only  an 
antiseptic  but  so  powerful  an  oxidizing  agent  that  it  re- 
moves diseased  tissue  and  pus,  leaving  the  healthy  tis- 
sue ready  to  heal.  Boric  acid  is  most  useful,  as  it  can  be 
put  on  thickly  and  then  the  wound  tied  up.  Alcohol  is 
not  antiseptic  except  when  concentrated,  and  the  same  is 
true  of  glycerin.  Copperas  is  used  for  drains  and 
closets.  It  leaves  an  iron  stain  if  it  dries  anywhere. 
Zinc  chloride  does  not  leave  a  stain  and  otherwise  acts 
about  like  copperas. 

Very  important  to  every  community  is  the  matter 
of  sewage  disposal.  A  country  house  can  easily  dis- 
pose of  its  sewage  by  simple  contrivances,  such  as 
properly  constructed  and  connected  cesspools  and 
drains.  The  first  receptacle  may  be  made  with  con- 
crete walls  and  is  called  a  septic  tank.  From  a  point 
well  down  in  this  tank  a  terra-cotta  pipe  is  fitted  which 
leads  up  along  the  wall  to  about  2J  feet  to  3  feet  below 
the  surface,  then  over  to  the  cesspool  proper.  The 

17 


258  CHEMISTRY  OF  FAMILIAR  THINGS 

cesspool  is  built  up  circularly  of  loose  stone,  making  a 
pool  about  eight  feet  in  diameter  and  of  varying  depth, 
say  eight  or  ten  feet.  The  upper  part  of  the  walls  is 
drawn  in  a  little,  and  the  whole  is  capped  with  large,  flat 
stones.  If  this  cesspool  is  in  loose,  sandy  soil  it  may 
be  all  that  is  required.  If  the  soil  is  clayey,  however, 
there  should  be  a  syphon  instead  of  a  cesspool  con- 
nected with  the  septic  tank,  and  a  branching  or  finger 
drain  about  2J  feet  below  the  surface,  in  the  direction 
in  which  the  ground  slopes  away,  and  on  ground  reced- 
ing from  the  house.  The  entrance  to  this  finger  drain 
must  be  below  the  level  of  the  drain  entering  from  the 
septic  tank.  An  architect  is  generally  requisite  for 
laying  out  an  adequate  system. 

The  chemical  action  is  in  two  stages.  That  in  the 
septic  tank  process  is  carried  on  practically  with  ex- 
clusion of  air.  An  energetic  fermentation  takes  place 
in  which  complex  organic  matter  is  broken  up  into 
simpler  substances.  All  the  waste  is  changed  into 
soluble  matter  and  harmless  gases.  Sven  paper  is  de- 
composed. This  thin  liquid  then  runs  into  the  porous 
cesspool,  where  it  is  acted  upon  by  air  in  the  loose  soil 
and  is  then  harmless  after  the  oxidation  which  takes 
place.  Protein  is  changed  into  ammonia  in  the  septic 
tank  and  it  is  oxidized  to  nitrites  and  nitrates  in  the 
ventilated  cesspool  or  finger  drain.  Harmful  bacteria 


CHEMISTRY  OF  THE  BODY  259 

are  themselves  killed,  due  to  tlie  taking  away  of  any 
food  for  them  to  live  upon  by  the  decomposition  proc- 
esses. What  is  done  in  the  case  of  a  single  house  can  be 
done  for  a  town  by  extended  construction  and  additions. 

Frequently  in  the  suburbs  of  large  cities  or  in  small 
towns  there  are  no  general  means  of  collecting  the 
sewage  and  treating  it,  but  every  house  has  its  own  way 
of  doing  it.  If  each  house  has  a  good  cesspool  construc- 
tion in  loose  soil,  where  the  ground  is  not  level  and  the 
houses  are  not  built  too  close,  the  method  outlined  may 
suffice;  but  the  writer  has  in  mind  small  suburban 
houses  built  on  25-foot  lots  in  rows,  and  then,  no  matter 
how  good  the  cesspools,  the  ground  becomes  impreg- 
nated with  unpurified  material.  In  these  latter  cases 
concrete  wells  should  be  used  and  cleaned  regularly,  or 
there  should  be  communal  methods  of  disposal. 

It  is  very  desirable  that  there  should  be  a  printed  list 
of  active  poisons  with  their  well-known  antidotes  in 
every  home  and  in  every  factory.  In  the  home  it  is 
better  to  exclude  such  poisons  when  there  is  no  sickness, 
as  there  is  no  shelf  high  enough  to  hide  them  success- 
fully. But  if  it  is  necessary  to  keep  on  hand  any  of  the 
well-known  poisons,  then  the  accompanying  table,  or 
a  similar  one,  which  may  easily  be  obtained  with  a  more 
extended  list,  should  be  put  on  the  door  of  the  medi- 
cine closet.  In  factories  particular  stress  should  be 
laid  on  the  antidotes  for  poisons  (all  strong  chemicals 


.260  CHEMISTRY  OF  FAMILIAR  THINGS 

are  poisons)  that  may  be  encountered,  such  as  strong 
acids,  carbolic  acid,  illuminating  gas,  arsenic,  etc. 

One  thing  of  which  the  writer  has  had  ample  proof 
is  the  poisonous  effect  of  nearly  all  gases,  except  oxy- 
gen or  air.  A  person  cannot  breathe  anything  except 
air  safely.  Even  relatively  small  quantities  of  gasolene, 
benzol,  chloroform,  carbon  tetrachloride,  hydrogen  sul- 
phide, and  coal  gas  will  asphyxiate  and  poison;  espe- 
cially the  two  latter  gases.  Carbon  monoxide  is  the 
most  active  poisonous  constituent  of  coal  gas.  It  acts 
as  a  reducing  agent  upon  the  blood  in  the  lungs,  and  hy- 
drogen sulphide  seems  to  do  the  same.  It  is  very  im- 
portant to  get  rid  of  any  corrosive  sublimate,  carbolic 
acid,  strychnine,  or  laudanum  if  they  are  left  in  a  house 
after  sickness,  or  at  most  leave  only  one  individual  dose 
in  the  bottle  for  a  possible  emergency. 

TABLE  OF  POISONS  AND  THEIR  ANTIDOTES." 

Emetic  9r  no 

Poison  emetic  First-aid  antidotes 

Hydrochloric  sulphu- 
ric,  nitric,  and 

oxalic  acids Give  no  emetic Magnesia,  four  ounces  to  one 

pint  of  water;  or  soap 
and  water;  or  chalk  or 
whiting  and  water  to 
drink. 

Ammonia ;  potassium 
and  sodium  hy- 
droxides   Give  no  emetic Lemon  juice  or  weak  vinegar 

to  drink. 

Corrosive  sublimate  .  Give  no  emetic Raw  eggs  beaten  up ;    flour 

and  water  or  milk. 

6  Largely  from  Funk  and  Wagnalls's  Encyclopedia. 


CHEMISTRY  OF  THE  BODY  261 

-  r 

Emetic  or  no 
Poison  emetic  First-aid  antidotes 

Phosphorus Give  emetic Magnesia  or  chalk  in  milk. 

Asphyxiating  gases .  .Give  no  emetic Fresh  air;  water  dashed  on 

head  and  chest;  artificial 
respiration. 

Opium,  laudanum, 

morphine,  chloral . .  Give  emetic Give    hot    coffee  ;    keep    pa- 
tient awake. 

Belladona    and   hen- 
bane   Give  emetic Give  hot  coffee  and  charcoal 

powder  and  water. 

Strychnine Give  emetic Give  20  grains  of  tannin  in 

water;  use  artificial  res- 
piration. 

Prussic   acid   and  cy- 
anide of  potash  ...If  possible  give 

emetic Stimulate  with  ammonia  and 

brandy;  dash  cold  water 
on  head  and  chest;  em- 
ploy artificial  respira- 
tion. 

Carbolic  acid Empty    stomach  very 

gently Quick  administration  of  al- 
cohol. Give  magnesia 
mixed  with  olive  oil; 
give  raw  eggs  and  milk. 

Aconite Give  emetic Stimulate  with  brandy  and 

water,  *apply  warmth  to 
extremities,  and  employ 
artificial  respiration. 

Lunar      caustic     ( ni- 
trate of  silver)  ...No  emetic  necessary .  Common  salt  is  most  effec- 
tive 

Alcohol Give  emetic Rouse  the  patient ;  give  hot 

coffee,  ammonium  car- 
bonate, and  apply 
warmth  to  the  extrem- 
ities ;  employ  artificial 
respiration  if  necessary. 


CHAPTER  XTIII 

SOAPS,  SOLVENTS,  AND  PAINTS 

THE  TEEM  "soap"  in  chemistry  applies  to  a  large 
range  of  substances  which  are  compounds  of  metal 
oxides  with  fatty  acids.  We  have  here  to  do  only  with 
the  alkali  soaps,  such  as  soda  or  potash  soaps.  These 
are  effective  for  cleaning  by  their  property  of  form- 
ing emulsions  with  grease  or  oil,  which  substances  seem 
to  be  the  great  dirt  fasteners.  Soap  is  the  great  dirt 
unfastener.  The  fatty  acids  are  derived  from  oils 
called  glycerides,  because  they  contain  glycerin  as  an 
integral  part,  just  as  salt  contains  chlorine  and  water 
contains  oxygen  chemically  combined.  When  boiled 
with  sodium  hydroxide  (lye)  the  glycerin  is  split  off 
from  the  fat,  because  it  has  less  chemical  affinity  for  the 
fatty  acid  than  has  the  sodium  hydroxide ;  consequently, 
soap  and  glycerin  are  formed. 

Sodium 

Stearin  hydroxide  Stearin  soap  Glycerin 

(Ci8H3602)  CsHg  +  3NaOH  —  CisHggO  .  O  Na  +  C3H6  ( OH)  3) 

Soap  was  probably  first  made  from  wood  ashes  thou- 
sands of  years  ago.  Wood  ashes  are  rich  in  potassium 
carbonate  (potash),  and,  on  boiling  a  liquor  of  this  with 
lime,  caustic  potash  lye  was  formed  which  made  soft 
soap.  To  what  extent  hard  soap  was  made  from  this  by 
262 


SOAPS,  SOLVENTS,  AND  PAINTS  263 

boiling  with  salt  is  not  known  to  the  writer,  but  such  a 
practice  probably  dates  back  some  time.  Such  a  trans- 
position or  chemical  reaction  expressed  partly  in  words 
would  be 

Potash  soap  +  NaCl  =  soda  soap  +  KC1  (potassium  chloride) 

Soaps  are  called  "hard"  if  made  from  soda  lye,  and 
"soft"  if  made  from  potash  lye.  We  are  mostly  con- 
cerned with  hard  soaps,  as  soft  soaps  are  chiefly  used 
in  textile  work  and  not  in  the  household. 

For  the  last  sixty  or  more  years  soaps  have  been 
made  from  sodium  hydroxide  produced  in  chemical 
works.  The  earliest  process  for  making  sodium  hy- 
droxide in  a  manufacturing  way  was  the  "Le  Blanc 
process,"  then  came  the  "ammonia-soda"  process,  and 
now  the  sodium  hydroxide  is  very  largely  made  by  elec- 
trolytic processes.  In  all  the  processes  salt  is  used  as 
the  starting-point.  , 

The  oils  most  used  for  soap  making  in  this  country 
are  tallow,  cotton-seed  oil,  distilled  grease  (from  gar- 
bage or  tankage  of  the  packing-houses),  cocoanut  and 
olive  oils.  In  addition  to  these  main  soap  stocks,  resin 
is  used  a  great  deal  in  soaps  for  laundry  purposes  and 
serves  a  useful  purpose,  as  we  will  see  later  on.  Tallow 
forms  a  hard  soap,  and  nearly  all  soaps  have  a  great 
deal  of  tallow  in  the  "stock,"  especially  hard  toilet 
soaps.  Hard  fats  are  more  in  demand  for  many  pur- 
poses, especially  soap  making,  than  liquid  fats  or  oils. 


264  CHEMISTRY  OF  FAMILIAR  THINGS 

Hard  fats  contain  more  hydrogen  than  liquid  fats,  and 
it  has  been  found  that  hydrogen  gas  can  be  efficiently 
combined  with  liquid  fats  in  the  presence  of  finely 
divided  nickel  as  a  catalytic  agent.  Liquid  cotton- 
seed oil  can  be  changed  into  a  solid  fat  like  tallow 
by  this  means.  The  chemistry  of  the  process  is  in 
the  reaction  of  olein  with  hydrogen  to  make  stearin, 
and,  as  olein  has  a  high  molecular  weight,  884.8,  and 
as  it  takes  only  3  molecules  of  hydrogen  with  a  weight 
of  6,  it  is  not  a  very  expensive  process,  taking  one 
part  of  hydrogen  to  form  148  parts  of  stearin.  This 
valuable  process  is  the  discovery  of  the  French  chemists 
Sabatier  and  Senderens.  Cotton-seed  oil  is  used  a  great 
deal  with  other  oils.  It  does  not  form  as  stiff  a  soap  as 
tallow  and  does  not  keep  well  in  a  soap  by  itself,  but  it 
renders  tallow  soap  more  soluble  and  is,  generally 
speaking,  a  good  soap  stock.  Distilled  recovered  grease 
makes  very  good  soap,  and  because  it  comes  from  gar- 
bage is  no  detriment.  It  is  used  in  the  best  soaps.  Co- 
coanut  oil  makes  saponification  proceed  more  readily 
when  it  is  present,  and  a  large  percentage  of  it  makes  a 
soap  that  can  be  used  with  salty  water  without  curdling. 
Such  soap  is  often  called  "marine"  soap.  It  also 
lathers  well  in  ordinary  water,  and  is  used  in  shaving 
soaps.  Olive  oil  forms  a  good  soap  which  is  much 
prized  by  some  people  under  the  name  of  "Castile" 
soap. 


SOAPS,  SOLVENTS,  AND  PAINTS  265 

There  are  several  ways  of  making  soap,  but  there  is 
only  one  of  ordinary  commercial  importance,  and  that  is 
to  saponify  the  fat  with  soda  lye  of  appropriate  strength 
while  the  contents  of  the  kettle  are  boiled  vigorously. 
When  the  "stock"  is  all  "cut,"  the  boiling  ceases  and 
the  soap  is  salted  out  so  as  to  separate  the  soap  from  the 
excess  of  the  alkali.  Water  is  added  and  a  little  lye, 
which  dissolves  the  separated  curd,  and  the  whole  is 
boiled  longer  to  complete  the  process,  and  salt  is  again 
added  and  the  spent  lye  run  off  a  second  time.  A  good 
deal  of  color  is  carried  off  each  time  in  the  spent  lye. 
The  soap-maker  learns  to  know  how  long  to  conduct 
each  operation  by  the  appearance,  and  there  is  a  chance 
for  the  display  of  nice  judgment. 

When  the  soap  has  stood  in  the  kettle,  say  overnight, 
so  as  to  allow  impurities  to  settle  out,  it  is  run  into  cool- 
ing frames,  and  if  castile  soap  is  being  made  it  is  simply 
cut  into  bars,  but  if  hard,  dry,  oval  cakes  of  toilet  soap 
are  to  be  made,  it  is  cut  into  chips,  dried  in  a  blowing 
oven,  and  mixed  with  color  and  perfume,  and  then 
squeezed  through  a  narrow  orifice  in  a  machine  called 
a  "pug  mill,"  by  means  of  a  screw,  and  automatically 
cut  into  cakes  and  pressed.  This  should  be  the  purest 
kind  of  soap,  as  it  contains  hardly  any  water,  say  5  per 
cent.,  and  wears  better  than  soft  wet  soaps. 

People  often,  however,  like  soap  to  float,  and  that 
is  the  easiest  kind  of  soap  to  make,  as  it  is  run  into  a 


266  CHEMISTRY  OF  FAMILIAR  THINGS 

machine  called  a  "crutcher"  when  cool  enough,  and 
air  is  pumped  in,  which  remains  in  it  as  very  fine  bubbles 
and  gives  buoyancy.  This  soap  has  the  natural  water, 
or  about  30  per  cent.  The  dry  soap  makes  a  smaller 
cake  for  the  same  weight,  but  it  is  nearly  all  soap,  while 
the  floating  soaps  are  largely  water  and  air.  The  writer 
does  not  want  to  be  misunderstood  as  holding  that  they 
are  a  fraud,  for  they  may  be  of  good  value,  but  the  old- 
time  hard  cake  has  desirable  properties  also.  Trans- 
parent soaps  are  rendered  so  by  the  use  of  glycerin, 
alcohol,  or  sugar.  The  former  is  probably  most  used. 

Laundry  soaps  generally  contain  resin,  which  acts 
like  true  soap  and  has  the  property  of  forming  very 
stable  emulsions,  so  that  its  use  may  be  a  real  benefit  in 
laundry  soaps.  Some  of  these  soaps  contain  naphtha, 
which  softens  the  grease  in  soiled  clothes.  The  use  of 
washing  soda  for  washing  purposes  is  a  proper  addition 
to  make,  to  the  extent  of  neutralizing  the  natural  hard- 
ness of  the  water  so  that  it  forms  good  and  fairly  per- 
manent suds.  One  or  two  tablespoonfuls  to  a  tub 
should  be  enough.  Borax  is  probably  a  safer  alkali  to 
use  than  washing  soda  or  soda  ash,  which  is  the  dry 
form  of  washing  soda,  but  in  regulated  quantity  soda  is 
satisfactory. 

Millions  of  dollars  have  been  spent  in  advertising 
soap  powders,  which  are  mixtures  of  soda  ash  and  a 
minor  amount  of  soap,  and  all  the  grades  are  more  or 


SOAPS,  SOLVENTS,  AND  PAINTS  267 

less  alike.  It  seems  more  reasonable  to  take  the  soda 
and  the  soap  separately  and  know  what  you  have  of  each 
substance.  Add  the  soda  to  soften  the  water  and  use 
the  soap  as  the  detergent.  This  is  an  excellent  plan  for 
bathing.  One  can  add  a  teaspoonful  of  soda  to  the  tub 
and  then  the  soap  will  not  form  a  curd  from  the  perspi- 
ration acids  of  the  skin.  The  writer  has  seen  a 
perfumed  article  consisting  of  washing  soda  and 
fragrant  oil  sold  at  the  rate  of  a  dollar  for  a  ten-ounce 
bottle.  It  had  a  French  name,  to  be  sure,  and  an  artis- 
tic label.  Scouring  soaps  contain  usually  fine  quartz  or 
silica.  The  silica  should  be  levigated  so  as  not  to 
scratch.  Pumice  is  used  as  powder  and  in  some  soaps 
for  severe  cases  of  soiled  hands.  Steel  wool  and  fine 
steel  shavings  are  good  articles  for  cleaning.  Used  wet 
they  will  clean  most  smooth  surfaces  perfectly. 

Solvents  are  only  useful  if  you  know  which  to  use. 
In  this  country  we  have  gained  in  recent  years  in  ac- 
quiring carbon  tetrachloride,  denatured  alcohol,  and 
cheap  pure  benzol.  Carbon  tetrachloride  is  chiefly  use- 
ful in  the  home,  because  it  will  not  burn.  It  is  not  very 
useful  for  extracting  greases,  etc.,  on  a  large  scale,  be- 
cause in  the  presence  of  water  it  gives  off  hydrochloric 
acid  (HC1),  which  attacks  metals  vigorously  and  would 
soon  ruin  steel  or  copper  vessels  in  which  it  was  used. 
Carbon  tetrachloride  may  not  be  obtainable  on  a  small 
scale,  in  which  case  the  manufacturer,  who  has  put  up  a 


268  CHEMISTRY  OF  FAMILIAR  THINGS 

solvent  containing,  along  with  naphtha,  sufficient  car- 
bon tetrachloride  to  prevent  the  mixture  igniting,  will 
win  out  and  you  will  take  home  a  handy  little  bottle  that 
will  do  all  that  is  expected  of  it.  The  writer  buys  this 
mixed  solvent  in  25-cent  bottles  rather  than  charge  his 
memory  with  taking  it  home  from  the  laboratory. 

In  general,  soapy  water  is  used  for  removing  sugar 
stains  from  clothes.  Carbon  tetrachloride,  benzine 
(gasolene),  and  benzol  (coal  tar)  are  effective  solvents 
for  grease.  Ink  stains  are  probably  best  removed  by 
means  of  oxalic  acid  solution,  which  is,  of  course,  a 
violent  poison  and  should  not  be  kept  on  hand. 

Oils  used  for  paints  and  similar  coatings  are  tech- 
nically known  as  drying  oils.  This  is  a  misnomer,  as 
they  do  not  dry  by  loss  of  moisture  but  by  oxidizing  on 
exposure  to  air.  On  taking  up  oxygen  they  become  thick 
and  finally  become  solid  and  lose  their  sticky  or  oily 
feel.  There  are  quite  a  number  of  such  oils,  as  walnut 
oil,  poppy-seed  oil,  soya-bean  and  Chinese-wood  oil, 
but  for  most  purposes  only  linseed  oil  need  be  con- 
sidered. The  first  two  oils  mentioned  are  used  some- 
what in  artists'  colors,  and  Chinese-wood  oil  is  used  in 
some  varnishes  and  oil  stains  after  a  heat  treatment 
which  toughens  it.  Chemists  measure  the  drying  proper- 
ties of  oils  by  their  ability  to  absorb  iodine,  as  iodine 
acts  somewhat  like  oxygen  in  uniting  with  some 


SOAPS,  SOLVENTS,  AND  PAINTS  269 

substances.    This  iodine  absorption  is  measured,  and 
is  called  the  iodine  figure  of  the  oil. 

The  iodine  figure  of  linseed  oil  is  very  characteristic, 
and  the  test  is  always  applied  to  linseed  oil. 

IODINE  FIGURES  OF  WELL-KNOWN  OILS 

Beeswax 8-11        Lard    57-63 

Cocoanut  oil 7-9         Olive  oil   81-85 

Butter  fat 26-35         Cotton-seed  oil    117-122 

Oleomargarine 55         Linseed  oil 175-190 

Tallow 36-40 

Pure,  fresh  linseed  oil  does  not  oxidize  very  rapidly, 
and  if  it  were  used  alone  in  paint  it  would  not  set  fast 
enough,  so  driers  are  put  in  which  induce  quick  setting, 
say  in  12  to  24  hours.  These  driers  contain  compounds 
of  lead  or  manganese  and  act  catalytically,  or  induce 
action  without  being  apparently  changed  themselves. 
So-called  "lotted  oils"  have  had  the  drying  treatment 
applied  to  them.  Boiled  oil  alone  is  used  as  a  natural 
wood  finish.  For  tops  of  dining-room  tables,  etc.,  it  is 
used  in  repeated  coats,  as  hot  dishes  do  not  affect  it. 
For  oaken  drain-boards  or  wood  that  is  often  wet  it 
serves  as  a  good  protective  coating.  If  it  can  be  ap- 
plied hot  it  will  penetrate  farther  then  when  used  cold. 

Paints  are  made  up  of  linseed  oil,  drier,  pigment, 
and  a  little  turpentine  as  a  thinner.  Volumes  of  contra- 
dictory matter  have  been  written  upon  the  pigments  in 
paint.  The  consensus  of  opinion  up  until  recently  has 
been  that  nothing  but  Dutch  white  lead  should  be  used 


270  CHEMISTRY  OF  FAMILIAR  THINGS 

except  as  tinting.  Recently  tests  have  seemed  to  show 
that  white  lead  with  associated  pigments,  such  as  zinc 
oxide,  levigated  barytes,  and  sublimed  white  lead, 
makes  the  most  durable  paints.  White  lead  alone  is 
likely  to  chalk  and  come  off  on  outside  work.  The  main 
thing  is  to  have  pure  boiled  linseed  oil,  however.  Lin- 
seed oil  is  used  in  linoleum  manufacture  by  undergoing 
an  oxidation  first  and  then  being  compressed  with  pow- 
dered cork. 

Turpentine  is  generally  used  as  the  thinner  for 
paint,  but  a  grade  of  petroleum  known  as  painters' 
naphtha  is  also  used,  and  has,  the  writer  believes,  de- 
cided advantages  which  outweigh  those  that  turpen- 
tine possesses.  Turpentine  is  supposed  to  assist  in  the 
drying  of  the  oil  as  it  evaporates,  which  may  well  be 
true,  as  turpentine  forms  ozone  on  evaporation,  but 
good  paint  oil  dries  fast  enough  anyhow,  and  naphtha 
does  not  have  the  penetrating  odor  of  turpentine. 

Stains  are  generally  alcohol,  turpentine,  or  varnish 
stains.  The  two  former  will  generally  give  the  best 
results,  as  the  varnish  films  are  not  apt  to  be  good  ones 
and  one  can  choose  what  after-coat  of  varnish  he  pre- 
fers when  simple  stains  are  used. 

Varnishes  are  good,  bad,  and  indifferent.  The  bad 
ones  are  made  from  rosin  with  China- wood  oil  or  a  very 
little  linseed  oil.  The  indifferent  ones  are  made  largely 
of  rosin  with  some  hard  resins  like  kauri,  manilla,  and 


SOAPS,  SOLVENTS,  AND  PAINTS  271 

copal,  and  boiled  or  thickened  linseed  oil.  The  good 
varnishes  have  little  if  any  rosin  and  the  proper  propor- 
tion of  hard  resin,  such  as  copal  or  dammar,  to  give  a 
hard,  elastic  surface. 

Spirit  varnishes  have  no  oil,  and  denatured  or  wood 
alcohol  is  used.  Eecently  several  men  lost  their  lives 
applying  shellac  cut  with  wood  alcohol  to  the  interior  of 
a  large  vat.  The  fumes  of  the  wood  alcohol  probably 
acted  as  a  specific  poison  and  killed  them.  The  fact  is, 
however,  that  nearly  any  organic  solvent  might  do  this 
in  a  confined  space.  The  writer  knows  from  personal 
experience  that  benzol,  carbon  disulphide,  and  gasolene 
tend  to  asphyxiate  when  the  vapors  are  inhaled 
strongly. 

Radiator  paints  are  composed  of  bronze  powders  in 
pyroxylin  lacquer  or  a  cheaper  lacquer  of  rosin  ester 
(a  manufactured  article  of  rosin  and  glycerin)  and 
naphtha, 

Paint  and  varnish  removers  have  come  into  use 
greatly  in  the  last  ten  years.  Before  their  advent  it 
used  to  be  necessary  to  burn  off  old  paint  or  use  alkalies 
such  as  ammonia.  These  removers  are  composed  of 
mixtures  such  as  wood  alcohol,  benzol,  and  fusel  oil, 
with  paraffin  in  suspension.  The  paraffin  acts  as  a 
sponge  and  holds  the  solvent  in  a  thick  layer  and  pro- 
tects it  from  too  rapid  evaporation  until  it  has  had  time 
to  dissolve  the  varnish  or  paint  film. 


272  CHEMISTRY  OF  FAMILIAR  THINGS 

Floor  and  furniture  oils  may  be  briefly  referred  to. 
For  waxed  floors  a  preparation  of  beeswax  and 
paraffin  in  fine  suspension  in  turpentine  is  useful.  This 
can  be  liquefied  by  warming  on  a  radiator  (not  a  stove 
or  near  fire  flame).  Another  formula  consists  in 
paraffin  which  has  been  dissolved  in  hot  mineral  oil  to 
the  extent  of  a  few  per  cent,  and  then  the  preparation 
is  allowed  to  cool,  so  that  the  paraffin  is  in  fine  suspen- 
sion, as  is  the  case  of  the  beeswax  and  paraffin  mixture. 
Floors  may  be  kept  in  good  condition  by  a  mixture  of 
thin  lubricating  oil,  such  as  light  machinery  (or  orange 
or  light-red  mineral)  oil,  with  ten  to  twenty  per  cent,  of 
linseed  oil.  Where  mops  are  used  for  oil  dusting  of 
floors  a  white  "neutral"  or  "spindle"  (odorless)  oil 
is  used. 


CHAPTEEXIX 

PAPEE  AND  TEXTILES 

DISCBIMINATING  people  demand  good  paper  as  they 
do  good  cloth  in  their  clothes.  Valuable  contributions 
to  literature  should  be  recorded  on  the  most  imperish- 
able paper  possible,  so  as  to  preserve  them.  It  is  also 
fitting  that  ephemeral  literature  made  only  to  sell 
should  be  consumed  to  carbon  dioxide  and  water 
rapidly,  as  seems  to  be  the  case,  due  to  the  prevalent 
use  of  ground  wood  in  cheap  paper. 

If  we  consider  labor  as  the  backbone  of  life,  we  must 
consider  paper  as  the  nervous  system  or  basis  upon 
which  all  work,  industry  and  recreation  are  regulated. 
We  find  that  animals  (or,  more  particularly,  insects) 
have  an  extremely  efficient  means  of  production  of 
paper.  We  have  all  seen  hornets'  nests.  These  are 
made  of  a  paper  pulp  that  is  produced  in  the  mouths  of 
the  hornets.  According  to  Dr.  S.  C.  Schmucker,  these 
insects  bite  off  fragments  of  wood  from  fence  rails,  etc., 
and  chew  it  until  the  pulp  is  produced.  Presumably 
the  enzymes  of  the  saliva  act  upon  the  ligneous  binding 
matter  and  reduce  the  pieces  to  pulp. 

Paper  is  essentially  composed  of  a  substance  known 
by  chemists  as  cellulose.  It  is  secreted  by  the  proto- 

18  273 


274  CHEMISTRY  OF  FAMILIAR  THINGS 

plasm  of  the  plant  to  form  rigid  cell  walls  that  when 
knit  together  will  form  a  skeleton  to  support  the  plant. 
The  ending  -ose  is  used  in  chemistry  to  signify  carbo- 
hydrates. These  have  been  referred  to  repeatedly 
under  foods.  Cellulose  has  the  same  relative  propor- 
tion of  carbon,  hydrogen,  and  oxygen  atoms  as  starch, 
but  evidently  the  total  numbers  of  atoms  in  the 
molecules  differ.  Both  are  written  (C6H1005)n:  "n" 
signifying  a  multiplier  greater  than  unity.  Starch 
occurs  in  more  or  less  rounded  or  oval  granules,  while 
cellulose  occurs  in  elongated  cells  that  intertwine  to 
form  a  rope  or  structural  shape  and  are  cemented  to- 
gether with  allied  substances.  In  woody  tissue  the  mate- 
rial is  lignin,  and  in  immature  plants  the  material  is  pec- 
tin or  similar  substance.  Both  lignin  and  pectin  are 
related  to  cellulose,  but  are  without  structure,  as  they 
are  used  for  cementing  or  binding  the  structural  sub- 
stance cellulose. 

In  early  times  stones  and  burned  clay  were  used  to 
record  events  of  national  importance  and  also  religious 
and  folk  lore.  We  note  in  early  Eoman  history  that 
writing  was  done  on  wax  with  a  pointed  instrument 
called  a  stylus.  Probably  about  this  time  writing  on 
dried  skins  called  parchment  began.  The  Chinese  and 
the  Egyptians  were  the  first  people  to  use  fibres.  The 
former  used  fibres  of  the  " paper-mulberry,"  which 
occur  matted  in  a  loose  cloth  or  paper.  The  latter 


PAPER  AND  TEXTILES  275 

used  strips  cut  from  the  stalks  of  the  papyrus  plant, 
which  were  woven  or  laid  so  that  the  edges  overlapped 
and  then  the  whole  was  wetted,  hammered,  and  dried  in 
the  sun. 

The  first  fibres  used  for  paper  that  were  made  into 
a  pulp,  so  far  as  seems  to  be  recorded,  were  flax  and 
rags,  mostly  of  linen.  Woolen  rags  could  not  be  used, 
and,  as  wool  was  worn  mostly  in  the  northern  countries 
of  Europe,  paper  was  made  first  in  Italy  and  Spain, 
where  lighter  clothing  was  in  vogue.  After  using  rags 
and  flax,  grasses  were  used,  especially  that  known  as 
esparto.  All  this  paper  was  made  by  pouring  the  pulp 
on  a  Screen  that  was  held  so  that  the  wire  mesh  was  just 
under  the  water.  After  oscillating  the  screen  to  make 
the  mass  of  uniform  thickness,  it  was  carefully  lifted 
so  that  the  water  went  through  and  left  the  fibres,  which 
were  removed  on  a  felt  or  cloth  and  when  dry  formed  a 
soft  paper.  Any  one  can  do  this  at  home  by  boiling 
chips  of  a  soft,  pithy  wood  with  sodium  hydroxide  (soda 
lye)  until  a  pulp  is  formed,  and  screening.  Straw  was 
also  used.  All  these  materials  supplied  cellulose,  and 
to  purify  it  from  adhering  substances  the  plants  or  rags 
were  allowed  to  ferment,  which  tended  to  free  the  cellu- 
lose fibres.  Paper  was  at  first  so  crude  that  important 
documents  were  legally  executed  only  upon  parchment. 
It  was  not  until  they  learned  to  use  some  kind  of  sizing 


276  CHEMISTRY  OF  FAMILIAR  THINGS 

or  glue,  with  fillers,  that  the  paper  was  reasonably 
strong  and  would  take  ink  without  its  running. 

In  England  paper  is  usually  made  from  wood  pulp, 
while  esparto,  which  is  imported  from  the  west  coast 
of  Africa,  comes  in  second,  and  rags,  used  so  far  as  the 
quantities  collected  allow  of,  rank  third.  In  the  United 
States  little  except  wood  is  used  for  making  paper  pulp. 
Those  most  used  are  coniferous  woods,  such  as  spruce 
and  hemlock,  and  poplar  where  the  latter  is  obtainable. 
Paper  does  not  look  much  like  wood.  It  differs  in  color, 
form,  and  texture,  but  we  will  soon  see  how  the  trans- 
formation is  effected. 

The  oldest  process  now  practised  for  making  paper 
uses  alkali.  Poplar  or  other  non-resinous  wood  is  used 
in  a  chipped  condition.  The  boiling  is  effected  in  closed 
kettles,  two  or  three  ordinary  stories  in  height  and  thor- 
oughly insulated  to  retain  the  heat,  which  rises,  because 
of  the  pressure  employed,  to  about  330°  to  365°  F., 
equivalent  to  a  pressure  of  100  to  150  pounds  per  square 
inch  above  the  atmospheric  pressure.  This  high  tem- 
perature facilitates  the  action  of  the  alkali  upon  the 
lignin  which  binds  the  fibres.  Nine-tenths  of  the  so- 
dium hydroxide  used  is  recovered  by  evaporating  the 
boiled-off  liquor,  burning  off  the  organic  matter,  and 
heating  with  lime.  When  sufficiently  cooked  the  con- 
tents of  the  digesters  are  run  off,  washed,  and  then  the 
fibres  are  beaten  with  water  until  they  are  all  loose  and 


PAPER  AND  TEXTILES  277 

separate.  This  material  is  ready  for  paper  making 
proper.  It  is  sold  in  loose  sheets  called  "half  stuff"  or 
"pulp,"  or  used  in  the  same  mill  to  make  paper.  It  is 
agitated  with  bleaching-powder  solution  to  whiten  and 
further  purify  it,  washed,  and  then  run  upon  the  paper- 
making  machine.  This  does  the  work  in  rather  better 
fashion  than  a  man  used  to  do  with  a  screen.  Generally 
size,  consisting  of  rosin,  soap  and  alum,  is  put  into  an 
agitator,  called  a  beating  engine,  with  the  pulp,  where  it 
is  sent  around  an  oval  race-course  with  water  by  means 
of  paddles  or  blades  that  revolve,  nearly  touching  other 
blades  forming  a  bed-plate.  Clay  and  other  fillers  and 
colors  are  also  put  in  at  this  stage.  The  clay  and  the 
size  fill  the  voids  in  the  paper  and  fix  the  colors.  The 
paper-making  machine  is  a  long  affair,  with  a  good 
many  parts :  for  making  the  magma  of  fibres  like  the 
hand  screen,  taking  it  off  in  felts,  rolling  it,  drying  and 
calendering  it  or  "ironing"  to  put  a  gloss  or  finish 
upon  it.  The  end  where  the  screen  is  is  called  the  wet 
end,  and  of  course  the  other  is  called  the  dry  end.  The 
whole  machine  is  often  considerably  over  100  feet  long 
and  makes  paper  up  to  18  feet  wide  and  in  continuous 
length  in  rolls. 

The  other  processes  are  similar,  except  the  cooking 
or  boiling.  One  process  is  "mechanical,"  in  that  the 
wood  is  ground  up  on  rapidly  revolving  grindstones  and 
is  then  made  at  once  into  paper.  Sulphate  pulp  is  much 


278  CHEMISTRY  OF  FAMILIAR  THINGS 

like  soda  pulp,  but  sulphate  of  soda  is  used  to  make  good 
the  loss  in  the  process  instead  of  sodium  hydroxide  or 
sodium  carbonate.  This  is  cheaper  and  it  makes  a  paper 
superior  for  many  purposes.  One  is  very  likely  to  hear 
of  Kraft  paper  nowadays.  Kraft  is  German  for 
strength.  This  paper  is  i i  soda  pulp ' '  in  which  less  soda 
is  used  and  the  intercellular  lignin  not  fully  removed,  so 
that  when  made  into  paper  it  acts  as  a  size  or  binder  for 
the  interlaced  fibres.  There  is  no  bleach  used,  and  the 
result  is  a  brown  paper  of  considerable  strength  used 
for  wrappings.  The  most  important  process  of  all  now 
is  the  sulphite  process,  although  the  sulphate  process 
has  made  inroads  into  the  business  recently.  In  the 
sulphite  process  the  cooking  is  done  in  tile-lined,  acid- 
proof  digesters,  with  a  liquor  made  by  passing  the  gas 
(sulphur  dioxide)  from  burning  sulphur  or  pyrites 
through  a  column  of  dolomitic  limestone  kept  wet  with 
water.  By  this  process  a  pulp  is  produced  that  is  easily 
bleached  and  can  be  used  for  a  great  variety  of  papers. 
The  water-mark  frequently  found  in  paper  is  an 
imprint  from  a  design  on  the  screen  at  the  wet  end  of 
the  press  or  on  the  first  drier  roll.  Paper  or  pasteboard 
boxes  are  made  from  old  paper  by  putting  it  through 
beaters,  which,  in  the  presence  of  water  alone,  break  it 
up  by  the  teeth  or  iron  paddles  of  a  revolving  drum, 
which  pass  over  stationary  teeth  called  a  "  bed-plate. " 
Color  is  generally  added  in  the  beaters  and  size  also. 


PAPER  AND  TEXTILES  279 

Several  thicknesses  are  often  united  by  means  of  sili- 
cate of  soda  when  used  for  box  boards. 

One  can  make  a  linen  or  a  bond  writing-paper  out  of 
chemical  wood  pulp  by  the  choice  of  pulp,  the  length  of 
time  it  is  beaten,  by  varying  the  size  and  the  pressure 
of  the  rolls.  Bags  are  used,  generally  mixed  with  wood 
pulp  in  the  best  writing-papers,  but  are  not  essential 
for  a  strong  and  fine-appearing  paper.  An  expert  can 
tell  by  means  of  a  microscope  what  kinds  of  fibres  are 
used  in  a  paper,  but  the  person  without  facilities  can 
judge  a  paper  only  by  its  appearance  and  its  resistance 
to  folding,  crumpling,  and  tearing.  Mechanical  wood 
pulp  is  easily  detected  by  merely  leaving  the  paper  in  the 
direct  sunlight  for  a  day  or  two,  when  it  turns  yellow. 
Art  and  coated  papers  and  cards  are  usually  sized  with 
casein  or  precipitated  milk  curd  made  into  a  paste  with 
alkali  or  borax  and  filled  with  clay.  This  coating  puts  a 
perfectly  smooth  finish  on  the  paper  when  calendered, 
so  that  illustrations  will  show  up  to  advantage.  Prac- 
tically all  book  papers  are  finished  with  size,  and  all 
surfaces  to  take  lithographic  impressions  are  heavily 
sized  and  loaded  with  clay. 

Paper  is  used  to  make  an  imitation  parchment  by 
passing  it  quickly  through  somewhat  diluted  sulphuric 
acid,  which  gelatinizes  the  outsides  of  the  fibres,  and 
when  the  excess  of  acid  is  washed  off  and  the  paper 
dried  it  has  lost  its  porous  condition  and  is  like  parch- 


280  CHEMISTRY  OF  FAMILIAR  THINGS, 

ment.  It  is  used  for  wrapping  butter,  lard,  bread,  etc. 
Instead  of  sulphuric  acid,  zinc  chloride  is  sometimes 
used,  which  acts  a  good  deal  the  same  as  sulphuric 
acid  by  abstracting  the  elements  of  water  from  the 
cellulose.  Layers  of  paper  treated  in  this  way  with  zinc 
chloride  are  compressed  to  form  what  are  called ' t  fibre ' ' 
articles  or  "hard  fibre."  It  is  used  for  trunks,  suit- 
cases, etc.,  and  for  electric  insulation.  When  paper 
pulp  is  beaten  a  long  time  it  swells  up  and  in  the  earlier 
stages  is  used  to  make  bond  and  India  paper,  and  when 
it  has  gone  practically  the  limit  of  the  process  for 
several  days  it  may  be  compressed  to  make  a  non- 
fibrous  substitute  for  celluloid,  called  "cellulith." 

Celluloid  itself  is  made  from  a  pure  white  tissue- 
paper  by  nitrating  with  a  mixture  of  sulphuric  acid 
and  nitric  acid.  This  nitro-cellulose,  when  heated 
with  camphor,  unites  to  form  celluloid.  The  trans- 
parent celluloid  is  the  purest  variety.  It  is  colored 
white  with  zinc  oxide,  and  other  pigments  are  used  for 
other  opaque  colors.  Transparent  goods  are  often 
colored  with  aniline  dyes.  Pyroxylin  is  moderately  ni- 
trated cellulose  and  is  used  for  the  finest  transparent 
lacquers.  Gun-cotton  is  fully  nitrated  cellulose.  There 
is  about  10  to  11  per  cent,  of  nitrogen  in  the  former  and 
13  per  cent,  in  the  latter.  Celluloid,  pyroxylin,  and  gun- 
cotton  all  flare  up  if  ignited,  but  do  not  ordinarily 
explode  in  small  quantities  unless  in  a  confined  space. , 


PAPER  AND  TEXTILES  281 

There  have  been  many  patents  taken  out  for  processes 
to  make  celluloid  non-inflammable. 

TEXTILES  is  a  subject  allied  to  that  of  paper.  If  the 
wood  fibres  were  long  enough  they  might  be  spun  into 
thread  and  woven  into  cloth.1 

Cord  and  rope  are  made  of  hemp  for  dark  grades 
and  cotton  for  the  white  grades.  Bagging  is  made  out 
of  jute,  which  is  a  first  cousin  to  hemp  and  a  second 
cousin  to  flax. 

All  the  pure  fibres  so  far  referred  to  are  made  up  of 
cellulose  or  a  compound  or  mixture  of  cellulose  and 
lignin  or  similar  substances  and  do  not  contain  nitro- 
gen. We  will  further  on  treat  of  wool  and  silk  fibres, 
which  are  entirely  different  from  cellulose  fibres  and 
contain  nitrogen.  One  can  tell  those  containing  nitro- 
gen by  holding  the  threads  in  the  flame  of  a  match.  They 
shrivel  up  and  give  off  ammonia  fumes  which  change 
moistened  red  litmus  blue  and  smell  like  burning  hair. 
With  this  test  artificial  silk  acts  just  like  cotton,  from 
which  it  is  made,  and  not  at  all  like  true  silk,  which  it 
resembles  only  in  appearance.  If  one  has  the  op- 
portunity to  examine  the  different  textiles  with  the 
microscope,  separate  a  few  of  the  fibres  from  one  of  the 


1  Cotton  fibres  are  from  20  to  40  millimetres  in  length. 
Flax  fibres  are  from  25  to  30  millimetres  in  length. 
Hemp  fibres  are  from  15  to  25  millimetres  in  length. 
Jute  fibres  are  from  1.5  to  4.0  millimetres  in  length. 
Esparto  fibres  are  from  0.5  to  3.0  millimetres  in  length. 


282  CHEMISTRY  OF  FAMILIAR  THINGS 

threads,  place  them  on  a  glass  slide,  wet  and  cover 
them  with  a  fine  glass  disk  called  a  cover-glass. 

MICROSCOPICAL  CHABACTEBISTICS  OF  FIBBES. 

Linen Jointed  fibres,  round  and  tapering. 

Cotton Twisted  bands  or  ribbons. 

Wool Filaments  with  overlapping  scales. 

Silk Smooth  fibres,  generally  in  pairs,  no  canals. 

Hairs Straight  filaments  much  like  wool,  but  with 

smoother  scales. 

Artificial  silk Smooth  single  fibres,  much  like  true  silk  in  ap- 
pearance. 

Cotton  grows  as  seed-hairs  which  are  designed  by 
nature  as  a  means  of  scattering  the  cotton-seeds  in  the 
wind  when  they  are  ripe.  It  is  separated  mechanically 
from  the  seeds  in  the  ginning  machine.  The  seeds  are 
pressed  to  furnish  a  valuable  oil,  and  the  residue  is 
known  as  cotton-seed  cake  or  meal,  and  is  a  valuable 
food  for  cattle.  The  fibres  go  through  mechanical 
operations  of  carding  (combing),  spinning,  and  weav- 
ing. Cotton  cloths,  muslins,  gingham,  outing  flannels, 
etc.,  are  cooler  than  the  same  weights  of  wool,  wash 
better,  are  stiffened  with  starch  better,  and  serve  alto- 
gether different  purposes.  Cotton  goods  are  apt  to  be 
so  heavily  sized  as  to  give  them  an  appearance  of  linen 
or  a  greater  fulness  than  they  would  naturally  possess. 
This  deception  can  be  detected  by  making  note  of  the 
number  of  threads  per  inch  or  their  size  as  compared 
with  other  goods  and  by  washing. 

Cotton  yarn  is  given  a  fine  lustrous  appearance 


PAPER  AND  TEXTILES  283 

called  mercerising  by  dipping  the  "hanks"  in  strong 
sodium  hydroxide  solution  while  under  tension,  wash- 
ing, and  drying.  It  takes  dyes  better  than  untreated 
cotton  and  has  a  silky  lustre. 

Linen  is  a  rather  finer  fibre  for  most  purposes  for 
which  cotton  is  suitable.  It  is  more  costly,  more  lus- 
trous, stronger,  and  lasts  longer  than  cotton.  Linen  is 
obtained  from  flax  by  breaking  and  retting  (a  fermen- 
tative change),  by  which  the  incrusting  matter  is  loos- 
ened from  the  cellulose.  Though  it  is  essentially  cellu- 
los.e  like  cotton,  the  fibres  are  tougher,  just  as  cotton  is 
stronger  and  more  durable  than  wood-pulp  cellulose. 

Wool  is  a  fibre  that  is  a  poor  conductor  of  heat.  It 
has  a  smooth  surface,  so  it  does  not  collect  dirt  as  much 
as  cotton,  when  the  two  are  woven  into  cloth.  Some 
woolen  fibres  are  very  soft  and  fine,  like  Australian 
wools  and  alpaca;  others  are  coarser  and  some  that 
merge  into  hair  are  so  coarse  and  stiff  that  they  are  suit- 
able only  for  carpets.  Wool  takes  dye  colors  better  than 
cotton.  In  fact,  there  are  only  a  few  dyes  that  fasten 
themselves  to  cotton  without  the  cotton  having  been 
treated  with  mordants  such  as  tannin  and  metallic  salts, 
while  there  are  only  a  few  that  do  not  readily  dye  wool. 
Advantage  of  this  fact  is  taken  in  testing  for  coal-tar 
colors  in  foods.  A  little  piece  of  white  nun's  veiling  is 
put  into  the  food,  after  being  thinned  out  with  water,  a 
few  drops  of  acid  added  and  brought  to  a  boil.  In  a 


284  CHEMISTRY  OF  FAMILIAR  THINGS 

little  while  the  woolen  cloth  will  become  highly  colored 
if  the  food  contains  a  coal-tar  color,  although  it  may 
take  up  some  slight  stain  from  vegetable  colors. 

BEHAVIOB  OF  CLOTH  TO  MINEBAL  ACIDS  AND  ALKALIES. 

Acid  Alkali 

Wool No  effect  Dissolves  if  concentrated. 

Silk No  effect  unless  con- 
centrated and  hot.  No  effect  unless  concentrated. 

Cotton Disintegrates  No  effect 

Artificial  silk Disintegrates  No  effect 

Cloth  that  contains  wool  and  cotton  can  be  analyzed 
to  find  the  percentages  of  both  substances  by  moisten- 
ing with  dilute  hydrochloric  acid  and  then  drying  out 
completely.  When  the  acid  becomes  concentrated  by 
drying,  it  attacks  the  cotton  fibres  so  that  they  fall  to 
pieces,  leaving  the  wool.  As  a  good  deal  of  this  union 
cloth  exists  and  as  the  wool  is  wanted  for  shoddy,  this 
process,  called  carbonization,  is  effected  and  the  wool 
is  reclaimed  and  used  in  cheap  clothing.  These  fibres 
of  shoddy  can  be  distinguished  from  untreated  wool  by 
their  broken  and  frayed  appearance,  especially  when 
seen  under  the  lens.  In  choosing  woolen  cloth  it  is 
well,  when  in  doubt  as  to  quality,  to  pull  out  the  fibres 
and  select  only  cloth  with  long  fibres  in  the  filling.  The 
warp,  which  is  the  skeleton  of  the  goods,  is  harder  to 
examine  and  not  quite  so  important  in  the  wear  in  most 
cases.  Where  both  classes  of  threads  (warp  and  filling) 
come  equally  to  the  surface,  their  quality  is  of  equal  im- 
portance. Wool  does  not  take  hot  soap  well  or  one  con- 


PAPER  AND  TEXTILES  285 

taining  any  alkali,  as  it  tends  to  felt  the  fibres  and  thus 
shrink  the  goods. 

Silk  is  a  good  insulating  fibre  like  wool ;  in  fact,  as  it 
is  finer  it  is  apt  to  be  a  warmer  covering.  It  wears  well 
because  it  is  both  tough  and  smooth.  Wool  is  apt  to 
catch  on  objects  because  of  its  curl  or  scales  and  thus 
wear  away,  but  silk  does  not  catch  and  as  a  result  wears 
very  much  better.  Silk  is  not  affected  unfavorably  by 
hot,  soapy  water. 

Artificial  silk  is  made  by  dissolving  cotton  or  a  com- 
pound of  cotton  in  a  suitable  solvent  and  throwing  it 
out  of  solution  or  combination  at  the  same  time  it  is 
forced  through  a  fine  opening,  thus  producing  a  thread. 
It  is  of  the  same  chemical  constitution  as  cotton.  Arti- 
ficial silk  is  made  from  cellulose  in  the  form  of  cotton, 
or  wood  pulp.  Pauly  silk  is  a  variety  made  by  dissolv- 
ing cotton  in  a  solution  of  copper  in  ammonia  and  then 
squirting  the  solution  through  fine  openings  called 
"  spinarettes "  into  sulphuric  acid.  The  thread  is 
washed  thoroughly  and  dried  under  some  little  tension 
to  give  it  the  maximum  degree  of  lustre.  Chardonnet 
silk  is  made  from  nitrocellulose  by  passing  a  solution  in 
alcohol-ether  through  spinarettes  into  water  containing 
calcium  sulphide,  which  takes  away  the  explosive 
character  by  removing  the  nitro-group  and  leaving  cel- 
lulose. Viscose  silk  is  made  by  the  interaction  of  so- 
dium hydroxide,  carbon  disulphide,  and  cellulose,  which 


286  CHEMISTRY  OF  FAMILIAR  THINGS 

make  a  xanthogenate.  Cellulose  is  reformed  by  spin- 
ning into  a  suitable  solution.  Acetyl  cellulose  is  also 
used  for  artificial  silk.  All  these  varieties  of  artificial 
silk  have  been  used  in  this  country  to  some  extent  and 
several  of  them  are  being  made  here.  They  are  not  so 
strong  as  true  silk,  especially  when  wet,  but  dye  in  all 
colors  and  are  used  in  braidings,  etc. 

Fire-proof  cotton  goods  have  been  successfully 
made  at  last,  by  a  process  devised  by  Dr.  W.  H.  Perkin, 
of  England.  He  uses  two  compounds  in  such  a  way  as 
to  produce  a  tin  salt  of  a  tin  acid,  which  is  rather  a  re- 
markable combination  but  very  effective.  Outing  cloth 
is  made  more  fire-resistant  than  wool  in  this  way. 


CHAPTER  XX 

LEATHER  AND  RUBBER 

LEATHER  and  rubber  are  not  related,  but  for  con- 
venience they  will  be  included  in  one  chapter.  To  un- 
derstand leather  we  should  know  how  it  is  derived,  and 
therefore  something  of  the  nature  of  hides  must  be  con- 
sidered. Skins  and  hides  are  made  up  of  two  layers, — 
the  epidermis  or  outer  skin  and  the  derma  or  true  skin. 
The  epidermis  consists  of  cells,  which  form  next  to  the 
derma  and  are  pushed  up  to  the  surface,  where  they  be- 
come flattened,  and  finally  are  worn  off  as  scales.  The 
epidermis  extends  down  the  hair-pits  to  the  end  of  the 
hair-roots,  and  when  unhairing  takes  place  in  making 
leather  the  epidermis  is  also  removed.  The  derma  con- 
sists of  fibrous  material,  or  coriin,  which  forms  the 
leather  on  tanning.  Fig.  6  (p.  288)  shows  the  essen- 
tial parts  of  a  section  of  skin,  with  hair,  hair-sheath, 
hair-erecting  muscle,  hair-papilla,  sweat-gland,  derma 
(C),  etc.  The  cuticle  can  be  seen  coming  down  into 
and  lining  the  hair-pit.  When  hide  is  fresh  it  is  soft 
and  pliable,  and  at  ordinary  temperatures  it  will 
putrefy  unless  treated  in  some  effective  manner.  If 
fresh  hide  be  boiled  with  water  the  collagen  contained 
is  largely  converted  into  glue,  while  the  associated 

287 


288 


CHEMISTRY  OF  FAMILIAR  THINGS 


coriin  remains  insoluble.  In  making  leather  all  ma- 
terial of  the  true  skin  or  hide  is  rendered  stable  under 
ordinary  conditions,  and  even  on  boiling  in  water,  no 
glue  is  formed. 

The  skins  of  goats  and  sheep  are  used  chiefly  for  light 
leathers,  and  those  of  calves,  cattle,  and  horses,  called 

hides,  for  heavy 
leathers.  Of  the 
lighter  grades, 
goatskins  are 
preferable,  a  s 
they  make  the 
beautiful,  light, 
yet  strong  mo- 
rocco, while 
sheep  skins 
form  a  similar 
leather,  but 
with  too  much 
stretch  in  it  for 

HlOSt 


FIG.  6.—  Section  of  hide. 

Calfskins  are  used  for  men's  uppers  when  morocco 
is  not  preferred,  and  the  thick  hides  of  cattle  are 
used  for  sole-leather.  Horse-hides  are  often  split  into 
two  layers  for  enamelling.  It  is  a  little  surprising 
how  the  machine  does  it  so  evenly,  thus  making  two 
thicknesses.  Other  machines  measure  the  number  of 


LEATHER  AND  RUBBER  289 

square  feet  of  an  irregular  skin,  with  "neck"  and 
"shanks." 

Until  recently  tannin-containing  materials,  such  as 
bark,  were  the  all-important  substances  for  making 
leather,  as  only  comparatively  little  leather  was  made 
by  alum  tawing  and  treating  with  fish  oil  or  chamoising. 
Now  the  great  and  growing  process  is  chrome  tanning. 
This  is  a  true  chemical  process  and  makes  more  water- 
resistant  leather  than  bark-tanned  leather.  Some  of  the 
materials  used  for  tannin  extracts  are  oak,  chestnut, 
and  hemlock  bark,  sumac,  myrobalans,  cutch,  etc.  No 
matter  what  the  tannage,  the  skins  must  be  unhaired 
by  soaking  in  lime  water,  and,  if  there  be  some  of  the 
old,  rank  lime  water  present  for  starting  new  baths,  all 
the  better;  as  bacteria  help  in  this  work,  as  they  do  in 
so  many  other  operations  favorable  or  unfavorable  to 
man's  schemes.  Often  the  bacterial  action  goes  too  far 
in  hot  weather  and  spoils  the  skins.  Ordinarily  in  a 
couple  of  weeks  the  hair  will  come  off  after  this  lime 
treatment,  which  is  finally  aided  by  men  with  knives, 
who  easily  scrape  it  off. 

After  the  unhairing  the  skins  are  washed  and  given 
a  bath  in  some  kind  of  dog,  pigeon,  or  other  puer  or  bate, 
which  swells  the  hides  and  draws  out  excess  of  lime. 
Latterly  artificial  puers  have  been  introduced.  Large 
hides  receive  a  fermenting  bran  "drench"  which  sup- 
plies lactic  acid  for  the  removal  of  lime.  After  more 
19 


290  CHEMISTRY  OF  FAMILIAR  THINGS 

washing  it  is  ready  for  tanning  with  bark  extract  for 
hides  and  bark  or  chrome  for  light  skins.  Personally, 
the  writer  is  more  familiar  with  chrome  tanning  and 
will  briefly  describe  the  process.  In  this  work  the  skins 
are  first  saturated  with  a  solution  of  sodium  or  potas- 
sium dichromate  and  hydrochloric  acid,  and  after  the 
excess  is  squeezed  out  they  are  put  into  a  bath  of  hypo- 
sulphite of  soda  (the  same  chemical  that  is  used  as  a 
fixative  in  photography).  This  reduces  the  chromate 
to  a  green  compound  of  chromic  oxide,  which  com- 
bines at  once  with  the  collagen,  the  interfibrous  cement, 
and  thus  makes  a  dense,  nearly  water-proof,  and  per- 
manent tissue.  There  is  still  plenty  to  do  in  making 
the  finished  article,  as  it  has  to  be  dyed  in  a  soapy  emul- 
sion, called  fat  liquor,  dried,  dampened,  worked  with 
glycerin  and  neat's-foot  oil,  stored  in  a  loft  a  while  to 
set  the  combinations,  and  then  dressed  with  gum  arabic, 
egg  albumin,  etc.,  and  "  ironed  "  with  heavy  glass  pieces 
on  a  special  machine  which  holds  both  leather  and  the 
glass  "iron." 

White  glove  leathers  are  often  treated  with  ^lum, 
which  does  not  tan  them  so  that  they  will  stand  water, 
but  merely  preserves  them,  and  they  are  softened  with 
something  like  egg  yolk.  This  treatment  leaves  the 
leather  pure  white,  while  chrome  tannage  gives  the 
leather  a  greenish  tinge  in  the  centre  where  the  dyes 
do  not  penetrate.  Bark-tanned  leather  is-  yellowish  to 


LEATHER  AND  RUBBER  291 

yellowish-red  throughout,  except  where  it  may  be 
stained  on  the  surface.  Oak-tanned  sole-leather  is 
light  in  color,  chestnut  is  medium  light,  but  hemlock  is 
reddish,  unless  it  has  been  bleached.  The  oak  and  chest- 
nut leathers  are  stronger.  Bark-tanned  leather  does 
not  resist  water  as  well  as  chrome-tanned  leather,  al- 
though all  leather  will  absorb  water  unless  saturated 
with  some  special  water-proofing  substance.  Neat's- 
foot  oil  tends  to  make  the  leather  water-proof  and  is 
good  for  the  leather,  but  for  uppers,  if  used  in  excess,  it 
prevents  the  shoes  taking  a  good  polish.  Some  water- 
proofing preparations  seem  to  consist  of  viscose  solu- 
tions. 

Besides  the  processes  mentioned  there  is  the 
chamois  process,  which  depends  upon  the  oxidation  of 
fish  oil  right  in  the  pores  of  the  skin. 

Sometimes  the  grain  surface  is  intentionally  rubbed 
off  of  morocco  leather,  which  gives  the  effect  known  as 
suede  leather.  Patent  leather  is  made  by  putting  a 
varnish  surface  on  the  rough  or  flesh  side  of  leather. 
The  varnish  is  made  of  linseed  oil  that  has  been  thick- 
ened with  heat  and  has  mineral  substances  present, 
such  as  dioxide  of  manganese  and  Prussian  blue,  which 
hasten  oxidation  or  drying  of  the  oil.  It  also  contains 
coloring  matter,  such  as  Prussian  blue  and  lamp-black. 
If  this  coating  is  put  on  the  grain  side,  it  is  called  enamel 
leather.  The  leather  must  be  degreased  before  being; 


292  CHEMISTRY  OF  FAMILIAR  THINGS 

made  into  enamel  leather  or  it  will  not  take  the  varnish 
so  that  it  will  stick  well.  Enamel  leather  is  less  likely  to 
crack  than  patent  leather,  as  it  is  on  the  grain  side, 
which  is  not  as  easily  stretched  as  the  flesh  side,  to  which 
the  patent  leather  surface  is  applied.  Very  little  stretch 
must  be  expected  of  either  of  these  treated  leathers, 
and  shoes  should  fit  when  first  tried  on.  To  preserve 
patent  or  enamel  leather  treat  with  an  oil  such  as 
neat's-foot  oil,  with  the  excess  rubbed  off,  or  use  a  good 
oil-paste  polish.  All  leather  is  better  for  a  little  oil. 
When  shoes  are  soled  they  should  have  rubber  cement 
between  the  leather  layers  so  they  will  not  rub  and 
squeak  if  the  layers  become  warped.  When  this  occur- 
rence happens  the  soles  should  be  soaked  a  while  in 
neat's-foot  oil. 

The  writer  has  often  wondered  why,  when  he  has 
tried  on  new  shoes,  they  seem  to  fit,  yet  when  they  have 
been  worn  a  while  they  pinch.  It  used  to  be  supposed 
that  it  was  due  to  lime  or  tannin.  There  should  not  be 
any  lime  in  leather,  or  it  would  cause  other  troubles  such 
as  lime  soaps,  which  bring  out  blotches,  and  it  cannot  be 
tannin  in  most  cases,  as  most  upper  leather  nowadays  is 
chrome  tanned.  It  would  be  most  reasonable  to  ascribe 
it  to  the  absorption  of  moisture  from  the  foot  and  conse- 
quent thickening  of  the  leather,  which  results  in  a 
shrinking  of  the  opening  for  the  foot.  When  leather 
becomes  stiff  it  can  often  be  improved  by  rubbing  it 


LEATHER  AND  RUBBER  293 

first  with  neat's-foot  oil  and  then  glycerin.  The  writer 
doubts  if  leather  can  be  rendered  water-proof  and  yet 
possess  pliability.  In  technical  work  it  is  impregnated 
with  rubber,  which  protects  the  leather  and  makes  it 
stronger.  Russia  leather  is  aoft,  bark-tanned  leather, 
impregnated  with  oil  of  birch,  which  gives  it  the  pe- 
culiar odor. 

Rubber. 

Eubber,  India-rubber,  or  caoutchouc 1  is  a  very  im- 
portant and  very  interesting  substance,  because  of  its 
properties.  Eubber  was  known  to  the  natives  of  trop- 
ical America  before  the  discovery  of  this  hemisphere, 
and  the  Spaniards  not  only  were  aware  of  its  use  for 
balls  but  used  the  milky  juice  of  the  plants,  called  latex, 
for  coating  garments  to  make  them  water-proof.  The 
fabrics  were  probably  dried  after  being  smeared  with 
the  latex,  when  the  rubber  particles  united  as  a  film. 
Before  or  at  the  beginning  of  the  eighteenth  century, 
apparently,  tubes  and  other  flexible  articles  were  made 
for  surgeons  and  chemists.2 

Early  in  the  nineteenth  century  raw  rubber  was  cast 
or  moulded  into  shoes  and  other  articles,  and  it  was 
not  until  1843  when  Goodyear,  an  American,  discovered 
that  heating  raw  rubber  with  sulphur  changed  its 

1  Caoutchouc  has  the  empirical  formula  Ci0Hi6. 

2  The  writer   finds   this   set   forth   in    Chaptal's   Chemistry,   trans- 
lated by  Professor  Woodhouse,  of  the  University  of  Pennsylvania,  1807. 


294  CHEMISTRY  OF  FAMILIAR  THINGS 

properties  so  that  surfaces  would  not  adhere  when 
pressed  together.  This  discovery  greatly  extended  its 
usefulness. 

Eubber  is  obtained  from  plants  of  the  EupJior- 
biacece,  chiefly  from  that  known  as  Hevea  Braziliensis. 
This  tree  grows  wild  in  the  forests  or  jungles  of  the 
Amazon  and  the  Orinoco  and  other  tropical  places,  and 
in  recent  years  has  been  grown  on  plantations.  So  far, 
the  native  article  from  the  Amazon  Valley,  known  as 
Para  rubber,  is  the  best. 

All  natural  rubber  contains  resinous  matter  which 
is  inelastic,  but  Para  rubber  contains  the  least  of  all, 
or  about  3  per  cent.,  African  about  10,  while  Guayule 
rubber,  which  is  obtained  from  a  small  plant  in  Mexico, 
contains  about  40  per  cent.  Eubber  from  the  Guayule 
is  not  very  elastic,  although  it  is  serviceable  for  some 
purposes  where  toughness  is  chiefly  requisite.  The 
resins  can  be  extracted  by  means  of  solvents,  such  as 
acetone,  and  this  has  apparently  been  done  by  some  of 
the  big  rubber-tire  companies,  as  the  writer  knows  of 
thousands  of  tons  of  these  resins  being  on  sale  where 
tires  are  made.  These  resins  are  closely  related  to  the 
true  rubber  or  caoutchouc  and  appear  to  be  oxidation 
products  of  the  same.  Pure  rubber  absorbs  oxygen 
from  the  air,  and  material  is  formed  similar  to  these 
naturally  occurring  resins.  Light  facilitates  this  oxida- 
tion, so  rubber  tires  should  be  kept  in  dark  places. 


LEATHER  AND  RUBBER  295 

The  purest  kind  of  rubber  is  now  made  syntheti- 
cally. Simultaneously  Professor  Harries,  in  Germany, 
and  Dr.  F.  E.  Matthews,  later  associated  with  Pro- 
fessors Perkins  and  Fernbach,  Sir  "William  Ramsay, 
E.  Halford  Strange,  and  others,  in  England,  succeeded 
in  making  rubber  economically.  In  England  it  was 
at  first  made  from  acetone,  and  later  from  fusel  oil. 
Means  were  also  found  of  obtaining  fusel  oil  quite 
cheaply  by  bacteriological  action,  more  directly  than 
formerly  made  as  a  by-product  in  the  production  of  al- 
cohol. Due  to  the  increased  production,  rubber  has  be- 
come much  cheaper,  and  it  will  probably  never  again 
rise  to  the  price  of  three  dollars  a  pound,  as  it  was  a  few 
years  ago. 

Vulcanization  of  rubber  is  effected  by  heating  it 
with  sulphur  or  certain  compounds  of  sulphur,  such  as 
antimony  sulphide.  As  sulphur  gases  would  tend  to 
form  on  heating  rubber  with  sulphur  alone,3  zinc  oxide 
is  generally  added  with  the  sulphur  to  absorb  them  by 
forming  zinc  sulphide.  The  temperature  of  vulcaniza- 
tion is  usually  about  275°  F.,  and  the  operation  is 
carried  out  in  closed  vessels,  or  autoclaves,  called  vul- 
canizers.  This  is  done  to  prevent  a  porous  condition  of 
the  rubber,  for,  even  if  zinc  oxide  is  used  to  absorb 
the  sulphur  gas  (hydrogen  sulphide),  water  would  be 


+  83  rrr 
H2S  +  ZnO  =  ZnS  +  H2O. 


296  CHEMISTRY  OF  FAMILIAR  THINGS 

formed,  and  if  it  tended  to  escape  the  goods  would  be 
spongy. 

Some  kinds  of  rubber  goods  cannot  be  subjected  to 
heat,  and  a  cold  process  is  carried  on  with  a  liquid 
combination  of  sulphur  and  chlorine  known  as  sulphur 
chloride.  Eain-coats  are  treated  this  way,  and  it  is 
necessary  to  have  zinc  oxide,  magnesium  oxide,  or 
alumina  (something  that  will  absorb  hydrochloric  acid) 
present,  as  some  of  this  acid  is  apt  to  be  evolved,  al- 
though this  formation  is  not  theoretically  the  result  of 
the  action,  as  both  the  sulphur  and  the  chlorine  are  sup- 
posed to  unite  with  the  rubber.4 

Vulcanised  rubber  or  hard  rubber,  for  fountain  pens, 
insulating  objects,  etc.,  is  made  by  using  25  to  40  per 
cent,  of  sulphur,  while  in  ordinary  processes  for  soft 
goods  2  to  3  per  cent,  is  used.  Bed  rubber  is  generally 
made  by  using  antimony  sulphide  (Sb2S5).  As  this  is 
not  as  strong  as.  sulphur,  it  is  necessary  to  use  about 
10  per  cent. 

Fillers  for  rubber  articles,  such  as  tires  for  auto- 
mobiles, are  composed  of  zinc  oxide,  fine  clays,  levigated 
barytes,  etc.  To  cheapen  the  rubber  and  render  it 
softer  and  more  workable,  to  neutralize  the  hardening 
effect  of  the  mineral  fillers,  and  to  make  it  less  ab- 
sorptive of  oxygen,  oils,  such  as  petroleum  oils,  blown 
petroleum  oils,  tar  products,  etc.,  are  incorporated.  The 

SC12  =  C/ioHie  .  SC12. 


LEATHER  AND  RUBBER  297 

writer  has  noticed  that  perfectly  pure,  unvulcanized 
rubber  becomes  brittle  sooner  than  loaded  goods.  The 
secret  of  making  good  tires  lies  in  removing  the  natural 
resins  and  adding  viscid  oils,  such  as  blown  petroleum, 
and  fine  neutral  mineral  fillers  with  some  basic  sub- 
stance, such  as  zinc  oxide. 

A  few  words  on  the  manufacture  of  some  of  the 
commonly  used  forms  of  rubber  may  be  of  interest. 
Rubber  shoes,  etc.,  are  made  by  coating  cloth  with  a 
mixture  of  rubber,  sulphur,  mineral  matter,  and  oils 
(for  the  inferior  grades,  reclaimed  rubber  also),  which 
has  been  calendered  to  thin  sheets  and  then  hot-rolled 
to  the  cloth.  Strips  of  this  rubberized  cloth  are  then 
stretched  over  lasts  and  when  all  formed  are  heated  in 
autoclaves  to  the  vulcanizing  temperature. 

Thin  sheets  for  dental  purposes,  tobacco-pouches, 
etc.,  are  also  made  by  forming  blocks  of  soft,  vulcanized 
rubber,  freezing,  and  then  cutting  with  rapidly  revolv- 
ing saws  regulated  by  micrometer  adjustment.  Rubber 
thread  is  made  by  winding  thin,  calendered  sheets  with 
talcum  powder  to  separate  them;  the  whole  is  tightly 
wound  and  vulcanized  and  then  cut,  according  to  size, 
transversely,  as  thin  sheets  are  cut.  Tubes  for  tires, 
etc.,  are  made  in  sheets  and  then  cemented  and  vul- 
canized. Automobile  shoes  are  made  up  on  forms  by 
hand  wrapping  layers  of  rubberized  fabric  and  rubber 
composition  and  then  moulded  with  excess  of  rubber 


298  CHEMISTRY  OF  FAMILIAR  THINGS 

composition  to  form  the  tread  and  vulcanized  in  the 
moulds.  Sometimes  they  are  vulcanized  without  the 
treads,  and  then  the  treads  are  vulcanized  afterwards. 

Direct  sunlight  and  moisture  act  upon  rubber  and 
weaken  it,  and  the  only  protection  is  to  keep  the  goods 
or  tires  in  as  dark  and  dry  a  place  as  possible.  Of 
course,  some  manufacturers  make  rubber  compositions 
that  are  more  resistant  than  others ;  but  it  is  hard  to 
determine  who  can  be  relied  upon  most,  as  the  tire 
companies  have  changed  their  mixtures  a  great  deal  in 
order  to  get  the  best,  so  one  year  one  may  be  ahead  and 
another  year  it  may  be  a  different  company.  With  tires 
it  is  not  only  the  rubber,  but  the  character  of  the  can- 
vas fabric,  its  amount,  method  of  application  and  union 
with  the  rubber  strata  that  are  important.  But  one  of 
the  main  points  in  regard  to  the  probable  wear  is  as- 
certained by  securing  strips  of  the  rubber  compound  in 
question  about  six  inches  long  and  about  one-eighth 
inch  square  section.  One  notes  about  how  far  an  inch 
measured  on  the  rubber  may  be  stretched.  It  should 
easily  stretch  to  three  inches.  When  released  it  is 
seen  how  near  to  the  original  marks  of  the  inch  length 
the  sample  finally  shows.  A  good  sample  should  not 
show  any  permanent  elongation. 

Any  one  can  determine  the  amount  of  mineral  matter 
in  rubber  by  ashing  a  weighed  sample  until  all  the  car- 
bon is  consumed  and  the  ash  is  light  in  color  and  then 


LEATHER  AND  RUBBER  299 

weighing  this  residue  on  an  accurate  balance.  When 
rubber  is  burned  and  the  flame  quickly  blown  out  the 
residue  is  very  sticky,  and  the  paste  makes  a  good  ce- 
ment for  some  purposes,  especially  if  mixed  with 
powdered  mineral  matter  of  some  kind. 

Cements  for  different  purposes  can  be  made  from 
chemicals  purchasable  at  any  drug  store.  A  strong 
water-  and  oil-proof  cement  is  made  by  mixing  litharge 
and  glycerin  to  a  stiff  paste.  It  sets  in  a  few  hours  to 
a  hard  substance.  SorePs  cement  is  valuable.  It  is 
made  by  mixing  a  strong  solution  of  magnesium  oxy- 
chloride  with  magnesia  (burned  magnesia)  to  a  stiff 
paste.  A  paste  made  by  mixing  concentrated  phos- 
phoric acid  and  zinc  oxide  sets  in  a  minute  or  two  to 
form  zinc  phosphate.  This  is  used  by  dentists  for 
filling  teeth.  Melted  gutta  percha  is  also  a  good  cement 
and  much  used  by  dentists*  Gutta  percha  is  chemically 
much  like  rubber,  but  it  is  stiffer  when  cold  and  softer 
when  hot.  This  makes  it  useful  for  a  cement  and  as  an 
insulation  and  protective  coating  for  transatlantic 
cables.  Gum  chicle,  used  for  chewing-gum,  and  balata, 
used  for  impregnating  belting  for  power  purposes,  are 
also  of  the  rubber  family. 


CHAPTEE  XXI 

SILICOUS  SUBSTANCES  AND  GLASS 

SILICA  is  the  most  widely  occurring  mineral  sub- 
stance in  the  earth's  crust.  Of  course,  we  do  not  know 
what  is  very  deep  in  the  interior,  although  astronomers 
and  geologists  have  made  clever  attempts  to  find  out, 
such  as  measuring  the  mutual  attraction  of  the  earth 
and  suspended  bodies.  Lava  flows  are  very  silicious, 
which  suggests  the  composition  well  below  the  surface. 

Silica  (Si02)  itelf  is  a  chemical  union  of  the  metal 
silicon  (Si)  and  oxygen.  Silicon  is  not  often  met  with, 
and  was  not  produced  in  a  commercial  way  until  a  few 
years  ago,  when  an  electrochemist  at  Niagara  Falls, 
C.  J.  Tone,  built  a  practical  electric  furnace  for  the 
purpose  by  which  he  produces  some  tons  a  day  of  the 
metal.  Silicon  is  used  in  steel  making  to  absorb  traces  of 
oxygen  and  thus  render  the  steel  denser  and  tougher. 
In  absorbing  this  oxygen  the  silicon  reverts  to  silica,  so 
silicon  is  not  accumulating  in  its  divorced  condition. 

Silica  has  never  been  much  used  by  itself,  but  re- 
cently tubes,  crucibles,  evaporating  dishes,  etc.,  have 
been  made  for  chemical  laboratories.  They  are  prov- 
ing very  useful,  as  they  stand  high  temperatures  and 
expand  so  little  by  heat  that  they  can  be  heated  to  red- 

300 


SILICIOUS  SUBSTANCES  AND  GLASS  301 

ness  and  then  plunged  at  once  into  cold  water  without 
cracking  at  all.  Every  one  knows  what  would  happen 
to  glass  under  such  circumstances.  It  seems  probable 
to  the  writer  that  such  ware  may  be  found  useful  in  the 
home  for  cooking  purposes,  as  nothing  injurious  would 
come  off  from  them  in  use.  Sudden  cooling  would  not 
hurt  them,  but  they  are  about  as  brittle  as  glass,  which 
they  resemble  closely  in  appearance,  and  they  could  not, 
therefore,  be  safely  dropped  on  the  floor.  Pressed- 
steel  and  cast-iron  vessels  are  enamelled  with  silicious 
compositions,  which  contain  borax  and  other  fluxes  to 
make  the  glaze  melt  at  low  enough  temperatures  to  be 
applied  cheaply.  There  are  enamels  made  in  this 
country  which  approximate  the  properties  of  silica,  are 
not  very  attackable  by  acids  or  other  corrosive  liquids, 
and  do  not  crack  off  easily  by  expansion.  They  are, 
however,  relatively  high-priced  and  are  used  for  dairy, 
food,  and  chemical  purposes. 

We  must  go  back  to  rocks  now  and  consider  silica 
free,  as  quartz,  and  in  grains,  as  sand,  and  also  silica1 
in  combination  with  basic  substances,  such  as  iron  oxide, 


Lead  oxide,  PbO 

Alumina,  A12O3 

Iron  oxides,  FesO3  or  FeO 

{Silicates 

1  Silica  (SiO2)       combines 
(acid  substance)         with 

Lime,  CaO 
Barium  oxide,  BaO 

t°f 
these 

Magnesia,  MgO 

bases 

Sodium  oxide,  NasO 

Potassium  oxide,  K2O 

(basic  substances) 

302  CHEMISTRY  OF  FAMILIAR  THINGS 

alumina  (aluminum  oxide),  lime  (calcium  oxide),  mag- 
nesia (magnesium  oxide). 

Eocks  are  more  practical  for  consideration  to  most 
of  us  than  ores  of  valuable  metals,  as  the  former  abound 
everywhere,  while  the  latter  are  found  only  in  spots 
and  are  dug  out  as  quickly  as  possible,  even  if  tunnels 
have  to  be  driven  to  find  them,  and  sent  to  the  smelter  to 
be  reduced  with  heat  and  coke  to  metals,  so  most 
of  us  do  not  see  them  in  their  natural  forms.  Eocks 
produce  soil,  give  contour  to  the  earth's  surface,  and 
are  useful  for  building  houses  and  roads.  Eocks  are 
known  from  their  earlier  origin,  or  later  origin,  as 
igneous,  sedimentary,  and  metamorpnic. 

Igneous  rocks  have  cooled  from  a  state  of  fusion  in 
the  location  substantially  where  found.  In  cooling,  the 
ingredients  separate  (except  in  the  case  of  obsidian 
or  natural  glass)  and  crystallize.  As  silica  is  apt  to  be 
in  excess  of  the  amount  necessary  to  form  silicates  with 
all  the  bases,  it  crystallizes  in  more  or  less  well-defined 
forms  throughout  the  mass.  When  the  crystallization 
is  well  defined  it  is  called  quartz.  Other  minerals 
separate  out  from  the  masses,  according  to  their  dif- 
ferent compositions,  in  crystals.  Granite  is  the  best 
example  of  these  igneous  rocks.  There  are  in  the  mass 
several  minerals  collectively  known  as  feldspar,  one 
variety  of  which  is  a  complex  silicate  of  potassium  and 
aluminum;  this  generally  is  slightly  pinkish  and  gives 


l>t-J^FT-  ***Xf 

f*  r.3w*ka?  J 
vj.%  t*«*-^i>; 

,.^^^/S 


^SiMf: 

ff*-^s   JW.#*iM: 


C.   Diorite,  some  feldspar. 


D.  Peridotite,  no  feldspar. 


Pirsson's  Rocks  and  Rock  Minerals:  Wiley. 

CONTRAST  OF  FELDSPATHIC  AND  FERROMAGNESIAN  ROCKS. 


SILICIOUS  SUBSTANCES  AND  GLASS  303 

most  of  the  characteristic  color  to  the  granite ;  there  are 
large  quantities  of  crystals  of  silica  which  are  glassy; 
and  then,  as  a  rule,  crystals  of  a  black  mineral  called 
hornblende,  which  is  a  complex  silicate  of  calcium,  mag- 
nesium, and  iron.  These  substances  were  all  dissem- 
inated when  hot,  but,  as  the  mass  cooled,  separation 
took  place  according  to  the  chemical  affinities,  and  the 
result  was  granite. 

Sedimentary  rocks  are  those  that  have  formed  after 
their  elements  have  been  worn  away  from  igneous  rocks 
and,  because  of  pressure  or  cementing  washes,  have  re- 
formed rock,  such  as  slate  and  sandstone.  The  former 
is  made  up  of  clay  compacted  by  pressure,  and  the 
latter  from  sand  by  percolation  of  silicious  waters  or 
great  pressure  and  some  cementing  substance.  Sedi- 
ments are  carried  by  wind  and  water,  but  they  are 
nearly  all  arranged  and  classified  by  water,  which 
carries  the  coarse  particles  only  short  distances,  the 
finer  particles  further  and  deposits  them  together,  and 
the  very  finest  grades  of  clay  are  carried  great  distances 
and  form  very  unctuous  clay  beds ;  some  of  these  have 
under  pressure  hardened  to  slate,  or  mixed  with  lime 
have  formed  more  or  less  argillaceous  limestones. 
Eocks  containing  the  proper  proportions  of  lime,  alumi- 
num, and  silica  are  burned  to  expel  carbon  dioxide  and 
water,  and  when  powdered  make  Portland  cement.  A 
great  deal  of  limestone  is  sedimentary,  as  is  referred  to 


304  CHEMISTRY  OF  FAMILIAR  THINGS 

in  Chapter  XI.  It  has  been  formed  from  the  calcareous 
skeletons  of  marine  animals  and  has  made  chalk  or,  if 
it  had  been  heated  under  pressure,  crystallized  lime- 
stone. Silicious  skeletons  of  microscopically  small  di- 
atoms have  been  carried  by  water  currents  and  de- 
posited in  strata,  sometimes  of  great  extent.  This  fine 
silica  is  called  infusorial  or  diatomaceous  earth  and  is 
used  for  insulation.  Metamorphic  rocks  are  those  that 
since  cooling  have  been  changed  by  some  agency,  such 
as  the  collection  of  partly  weathered  rock  particles,  into 
fresh  rock  aggregates  by  means  of  streams  of  igneous 
matter,  or  heat  and  pressure,  etc.  It  was  always  in- 
teresting to  the  writer  to  see  stratified  rocks  in  railroad 
cuts ;  to  realize  how  they  were  distorted  at  one  time  by 
unequal  pressure  from  below,  when  the  earth's  crust 
was  thinner;  to  note  how  they  were  worn  away  un- 
equally at  the  surface,  where  evidence  shows,  from  the 
direction  of  the  strata,  that  land  miles  higher  than  now 
exists  was  worn  away  and  carried  into  the  sea.  These 
agencies  of  change  have  always  been  at  work  and  will 
doubtless  continue,  although  it  is  probable  that  the  rate 
of  change  is  much  slower  now  than  it  once  was ;  for  in- 
stance, at  a  time  when  the  water  on  the  earth's  surface 
was  so  heated  from  below  that,  like  a  vast  hot-water 
heating  system,  it  provided  a  tropical  atmosphere  even 
at  the  poles.  At  such  a  time,  when  there  were  also  larger 
amounts  of  carbon-dioxide  gas,  which  has  since  been 


SILICIOUS  SUBSTANCES  AND  GLASS  305 

deposited  as  coal,  the  attack  on  mineral  aggregates, 
such  as  limestone  and  feldspar,  by  the  conjoint  action  of 
heat,  water  vapor,  and  carbon  dioxide  was  greatest,  and 
as  the  rock  obtruded  it  crumbled  rapidly  in  compari- 
son with  the  present  rate. 

Stone  for  building  should  be  such  as  will  stand  the 
weather  reasonably  well.  Some  rock  is  nearly  all  silica, 
known  as  quartzite,  and  is  practically  everlasting.  The 
writer  was  fortunate  in  getting  this  stone  for  his  house, 
but  it  was  not  a  beautiful  stone  by  itself  and  so  was 
covered  up  with  cement  plaster.  Granite  is  about  the 
most  durable  building  stone  we  have,  although  it  does 
not  resist  fire  well,  due  to  traces  of  water  inclosed  in 
the  silica,  which  expands,  and  then  the  several  min- 
erals separate.  After  this  probably  come  micaceous 
rocks  of  uniform  dense  structure.  Some  schists  have 
not  had  sufficient  metamorphic  action  to  be  enduring. 
Dense  crystalline  marbles  are  structurally  firm,  al- 
though carbon  dioxide  may  wear  away  the  surfaces 
very  slowly,  and  if  the  spaces  between  crystals  are  great 
enough  the  decay  is  more  rapid.  The  stones  used  some- 
times for  building  which  have  been  conspicuous  for 
weathering,  besides  mica  schist,  are  serpentine  (a  hy- 
drated  silicate  of  magnesium),  sandstones  (particularly 
brown  sandstones  which  contain  iron),  and  I  might  add 
bricks  that  are  not  hard  burned. 

Road  stones  must  be  as  hard  as  possible,  even  if  the 

20 


306  CHEMISTRY  OF  FAMILIAR  THINGS 

road  is  made  with  an  asphaltic  or  pitch  binder.  Crushed 
limestone  is  frequently  used  for  this  purpose,  because 
of  its  cheapness  in  certain  localities.  For  little-used 
private  roads  it  is  probably  the  best  material,  for  it  be- 
comes well  cemented  together  by  the  rain,  especially  if 
there  be  a  proportion  of  "fines."  Oyster-shell  roads, 
that  are  sometimes  met  with  near  the  coast,  are  well 
known  for  their  firm,  smooth  surfaces.  For  public 
roads,  however,  limestone  does  not  do  at  all,  as  it  is 
promptly  crushed  to  powder  by  traffic,  even  if  there  be 
a  binder.  Trap  rock  is  most  in  demand,  as  it  is  very 
hard.  On  hill  and  mountain  slopes  the  rocks  that  stand 
out  from  the  soil  and  have  survived  the  general  decay 
are  usually  trap  rock,  which  is  a  kind  of  basalt,  of 
igneous  origin. 

The  rocks  that  are  most  found  can  be  analyzed  suf- 
ficiently for  identification  by  any  one.  A  blade  of  a 
pocket-knife  will  scratch  nearly  all  but  silica.  Of  course, 
corundum  and  garnet  are  too  hard  to  scratch,  but  they 
are  not  abundant.  Limestones  will  effervesce  with  acid 
(vinegar).  Feldspar  is  softer  than  silica  (may  be 
scratched  with  knife-blade),  is  generally  pinkish,  al- 
though sometimes  green  or  grayish.  It  is  not  as 
vitreous  as  silica.  Mica  is  known  by  its  scales.  Horn- 
blende is  hard  and  coal  black. 

Glass  occurs  in  nature  as  a  volcanic  effusion  known 


SILICIOUS  SUBSTANCES  AND  GLASS  307 

as  obsidian,  but  man  prefers  to  make  his  own  rather 
than  use  nature's. 

Glass  making  is  an  interesting  line  of  manufacture, 
and  spectacular  as  well,  for  the  handling  of  large  ladles 
of  molten  glass  is  very  impressive,  and  the  moulding 
of  masses  for  plate-glass,  the  blowing  of  large  cylin- 
ders for  window-glass  by  mechanical  means,  and  the 
blowing  of  smaller  bubbles  by  human  lung-power,  are 
sights  to  be  remembered.  One  of  the  writer's  children 
at  the  age  of  three  asked  him,  in  a  "brogue"  charac- 
teristic of  that  time  of  life,  what  glass  was  made  of. 
He  was  told  that  it  was  made  of  sand.  This  was  not 
enough,  so  he  asked  what  made  the  sand  "  'tick  to- 
gether," which  was  a  thoughtful  observation.  They 
use  very  pure  white  silica  sand  and  make  it  stick  to- 
gether by  heating  it  with  some  form  of  soda,  such  as 
sodium  sulphate  or  soda  ash,  and  pure  lime.  This 
makes  a  compound  silicate  of  soda  and  lime,  and  this 
general  composition  is  used  for  most  purposes,  such  as 
windows,  bottles,  and  ordinary  moulded  articles.  For 
cheap  bottle  glass  iron-containing  sand  is  used,  which 
produces  a  greenish  color.  This  is  neutralized  in  some 
cases  with  manganese.  In  old  houses  one  often  sees 
purple  panes  of  glass  in  the  windows.  These  are  highly 
prized  by  the  old  families.  This  glass  had  manganese 
added  to  neutralize  the  color  due  to  iron,  and  by  the 


308  CHEMISTRY  OF  FAMILIAR  THINGS 

action  of  light  the  purple  color  has  probably  been 
formed. 

In  Germany  glass  was  made  originally  from  wood 
ashes,  which  are  rich  in  potash.  They  still  make  potash 
glass  which  is  called  Bohemian  glass,  and  is  more  in- 
fusible than  other  glass  and  used  for  combustion  tubes 
in  the  laboratory.  Jena  glass,  used  for  thermometers 
and  chemical  ware,  contains  borax  and  some  alumina. 
The  most  beautiful  glass  is  potash-lead  silicate,  or  flint 
glass.  It  has  a  high  index  of  refraction  and  conse- 
quently has  a  more  brilliant  appearance,  especially  when 
cut.  This  composition  is  used  for  so-called  " paste" 
diamonds  and  for  optical  purposes.  It  is  not  as  in- 
soluble in  water  as  other  glasses.  Some  glasses  are 
lime-potash-soda  silicates,  and  are  used  as  enamels 
for  buttons,  pin-heads,  and  cheap  jewelry. 

Iron — green  Sulphur — black 

Cobalt — blue  Gold — ruby-red 

Antimony — yellow  Manganese  dioxide — violet-red 

Uranium — opalescent  yellow  Phosphate  or  cryolite — white. 

The  colors  in  glass  are  due  to  metallic  oxides.  By  the 
addition  of  carefully  selected  oxides  glass  is  made  that 
will  shut  out  certain  rays  of  light  without  affecting 
others.  Sir  William  Crookes  has  invented  a  special 
glass,  for  instance,  that  will  shut  out  98  per  cent,  of  heat 
rays,  and  another  that  eliminates  the  ultra-violet  rays. 
Glass  is  toughened  by  plunging  it  into  oil  while  hot. 


SILICIOUS  SUBSTANCES  AND  GLASS  309 

Clay  ware,  which  includes  earthen-ware,  chinaware, 
and  porcelain,  differs  from  glass  in  that  a  natural  sili- 
cate is  used  which  does  not  fuse  in  the  manufacture, 
although  it  softens  more  or  less. 

Earthen-ware  is  made  from  clay  which  does  not 
burn  very  white.  As  a  rule,  it  is  cheap  clay  and 
the  finished  article  has  no  claim  for  either  beauty  or 
strength.  It  is  made  in  a  single  burning  and  the  glaze 
is  due  to  saline  matter  on  the  surface.  This  salt  is 
thrown  into  the  kiln  and  volatilizes  first,  permeates  the 
kiln  and  then  unites  with  the  biscuit-ware,  forming  a 
more  or  less  dense  coating. 

Porcelain  is  made  from  white  kaolin  or  clay,  which 
is  a  silicate  of  aluminum  and  free  from  iron.  Some 
feldspar  is  mixed  with  the  clay  to  make  it  fusible  enough 
to  close  the  pores,  and  silica  to  reduce  the  shrinkage  on 
firing.  When  the  ware  comes  out  of  the  kilns  it  is  white, 
dull,  and  somewhat  porous.  This  is  called  biscuit- ware, 
and  it  is  washed  with  a  fusible  glaze  ground  up  in  water 
and  returned  to  the  kiln.  The  ware  then  becomes 
lustrous  when  finished. 

The  chemistry  of  all  porcelain  work  is  largely  the 
same, but  the  excellence  of  the  workmanship  in  moulding 
and  character  of  the  clay,  the  slight  differences  in  the 
composition  of  the  glazes,  and  the  skill  of  the  deco- 
rators determine  the  character  of  the  ware.  If  porce- 
lain wares  were  piled  one  upon  another  in  kilns  the 


310  CHEMISTRY  OF  FAMILIAR  THINGS 

glazes  would  cement  them  together.  The  glaze  is  re- 
moved from  the  under  rim  and  they  are  set  in  fire-clay 
receptacles  called  saggers.  In  cheap  ware  there  are 
small  three-pointed  spiders  that  separate  the  plates 
and  touch  the  bottom  and  top  of  each  in  three  places. 
At  these  points  the  glaze  is  spoiled. 

An  important  line  of  manufacture  has  grown  up  in 
recent  years  in  the  making  of  glazed  building  tiles.  This 
seems  like  a  nearly  ideal  building  material  if  the  glaze 
is  insoluble,  as  there  are  no  appreciable  cracks  or  pores 
for  the  moisture  to  get  in  and  then  to  freeze  and  break 
down  the  structure,  as  happens  in  much  of  the  brick 
used.  With  reference  to  brick,  the  only  kind  of  brick 
that  would  seem  entirely  satisfactory  for  building  is  the 
very  high-temperature  brick  called  "down  draught"  or 
that  made  in  pottery  kilns. 

A  few  words  might  be  said  about  precious  stones. 
The  chemist  has  finally  succeeded  in  making  practically 
all  of  them, — not  cheap  imitations,  but  the  real  articles. 
Diamonds  are  made  artificially  that  are  just  the  same 
in  composition — namely,  pure  carbon — as  the  natural 
ones.  The  great  French  chemist,  Moissan,  as  is  well 
known,  has  made  small  diamonds  by  placing  some  sugar 
carbon  in  a  sealed  iron  container  and  then  plunging  it 
into  a  bath  of  molten  iron.  Carbide  of  iron  is  formed  by 
the  union  of  carbon  and  iron.  The  outside  of  the  iron  is 
then  chilled  with  water,  which  causes  a  contraction,  and 


SILICIOUS  SUBSTANCES  AND  GLASS  311 

this  subjects  the  interior  to  great  pressure.  As  the  car- 
bon is  thrown  out  of  solution  in  the  iron  on  cooling 
at  high  pressure,  very  small  diamonds  are  formed, 
which  are  recovered  by  dissolving  away  the  iron  with 
acid.  Eubies  and  sapphires  are  crystallized  alumina  col- 
ored with  metallic  oxides.  They  have  been  made  in  the 
laboratory  by  fusing  alumina  with  traces  of  oxides  in 
the  heat  of  a  blow-pipe  in  an  ingenious  way  devised  by 
Verneuil.  The  flame  of  the  blow-pipe  carries  finely 
powdered  alumina  with  coloring  oxides,  such  as  chro- 
mium, and  builds  up  drops  of  crystalline  material,  which 
constitute  the  gems.  These  stones  are  the  same  in 
composition,  appearance,  and  properties  as  those  natu- 
rally occurring.  The  emerald  is  silicate  of  beryllium,  or 
beryl,  with  a  trace  of  chromium.  Topaz  is  a  silicate  of 
aluminum  and  is  harder  than  quartz.  It  is  generally 
yellow  to  brownish-yellow  in  color. 

Portland  cement,  known  in  the  time  of  ancient  Eome, 
has  been  rediscovered  in  comparatively  recent  times. 
It  has  become,  after  wood,  probably  the  most  important 
building  material  we  have.  Building  with  cement  is 
fire-proof,  weather-proof,  and,  when  reinforced  with 
steel  rods,  of  enduring  character.  It  is  normally  not 
quite  water-proof,  but  by  putting  in  mixtures  contain- 
ing fish  oil,  etc.,  in  proper  amount,  it  is  made  water- 
proof. 

Portland  cement  is  made  by  heating  to  a  white  heat 


312  CHEMISTRY  OF  FAMILIAR  THINGS 

sand,  clay,  and  limestone, — calcareous  clay,  or  argil- 
laceous limestones,  or  any  mixtures  of  silica,  alumina, 
and  lime  that  on  burning  would  give  a  resultant  mixture 
that  contains,  approximately,  lime  65  per  cent.,  alumina 
25  per  cent.,  and  silica  10  per  cent. ;  a  little  iron  may  re- 
place alumina.  The  clinker  so  formed  must  be  ground 
to  impalpable  fineness.  Magnesium  compounds  and  sul- 
phates in  very  appreciable  amounts  are  undesirable 
constituents  of  Portland  cement.  Cement  coatings  seem 
to  protect  steel  from  corrosion  except  where  stray  elec- 
tric currents  may  cause  corrosion  in  damp  places.  In 
the  setting  of  Portland  cement  several  lime  compounds 
are  formed,  such  as  calcium  silicates  and  calcium  alu- 
minates,  which  in  crystallizing  with  water,  in  the  same 
way  that  plaster  of  Paris  does,  cause  a  setting,  or  form 
a  monolith,  where  a  form  is  prepared  for  it,  with  the 
sand  and  stone  used  as  diluents. 

The  value  of  cement  is  determined  by  making  bri- 
quettes, with  sand,  that  have  a  square  inch  cross  section 
in  the  narrowest  part.  After  the  briquette  has  been 
properly  set  with  water  it  is  put  under  a  pulling  strain 
and  the  number  of  pounds  taken  to  break  it  are  noted. 

Asbestos  is  silicate  of  magnesium  which,  according 
to  variety,  may  also  contain  associated  silicate  of  iron, 
alumina,  or  lime.  It  is  valuable  for  its  fibrous  structure. 
It  is  chemically  related  to  other  well-known  minerals, 
such  as  talc,  serpentine,  and  meerschaum,  which  are 


SILICIOUS  SUBSTANCES  AND  GLASS  313 

simple  magnesium  silicates,  and  hornblende  is  a  lime- 
magnesia  silicate  containing  iron. 

Asbestos  as  loose  packing  or  corrugated  sheets  is 
a  good  heat  insulator  and  has  quite  a  reputation  for 
withstanding  the  intense  heat  of  direct  fire.  Flame 
applied  directly  does  not  melt  or  consume  it,  but  it  takes 
away  its  life  by  rendering  it  quite  brittle.  For  curtains 
and  fabrics,  such  as  automobile  brake  linings,  where 
strength  is  required,  it  is  woven  with  copper  or  brass 
wire.  Brake  linings  are  also  impregnated  with  some 
tough  paint  or  varnish  such  as  montan  wax.  Asbestos 
for  insulation  has  given  ground  a  little  of  late  to  well- 
packed  infusorial  earth,  diatomaceous  earth,  or  (Ger- 
man) Kieselguhr. 


CHAPTER  XXII 

A  FEW  IMPOKTANT  DEFINITIONS 

ADSOKPTION  is  the  abstraction  and  retention  of 
matter  from  solution  by  insoluble  substances,  generally 
as  powders  in  suspension.  It  seems  to  be  a  quasi-chem- 
ical attraction  without  chemical  change.  It  is  a  phys- 
ical change.  The  composition  of  the  matter  in  solu- 
tion and  that  of  the  powder  largely  determines  the 
phenomena,  although  the  structure  of  the  powder 
is  a  vital  element.  Adsorption  differs  from  absorp- 
tion in  signifying  a  drawing  to  rather  than  a  draw- 
ing in.  Examples  of  adsorption  are  the  clarification 
and  decolorization  of  oils  with  fullers'  earth;  the  re- 
moval of  oily  turbidity  from  aqueous  liquids  with  mag- 
nesia; the  removal  of  dye  from  aqueous  solution  with 
fine  silica  or  aluminum  hydroxide,  etc. 

Catalytic  agents  are  substances  that  induce  chemical 
changes  without  being  themselves  altered  in  composi- 
tion. Examples  of  this  action  are :  A  platinum  sponge 
acting  to  cause  ignition  of  gas  in  the  presence  of  air; 
finely  divided  nickel  acting  to  cause  the  hydrogenation 
of  liquid  fats ;  iron  oxide  causing  the  union,  under  heat 
and  pressure,  of  hydrogen  and  nitrogen  to  form  am- 
monia. 

Enzyme  action  is  really  catalytic  action,  as  the  en- 
zyme simply  induces  the  chemical  change.  Examples  of 

314 


A  FEW  IMPORTANT  DEFINITIONS  315 

enzyme  action  are  the  action  of  diastase  in  forming 
sugars  from  the  starch  in  malt,  chlorophyll  in  inducing 
the  union  of  carbon  dioxide  and  water  to  make  formal- 
dehyde as  a  step  in  making  carbohydrates,  and  the 
action  of  the  digestive  juices.  They  are  organic  cat- 
alysts. 

Colloid  chemistry  deals  with  particles  of  matter  in 
such  fine  suspension  in  liquids  that  they  approach  a 
true  solution.  These  particles  cannot  of  themselves  be 
seen  with  the  most  powerful  microscope,  but  by  the 
reflection  of  light  from  these  particles  their  suspension 
can  be  noted  by  a  microscope  fitted  up  for  this  purpose, 
called  the  ultra  microscope.  The  fine  particles  of  purple 
of  Cassius  and  gelatin  and  agar-agar  jellies  are  ex- 
amples of  colloids.  The  present  knowledge  as  to  col- 
loids is  verV  helpful  in  explaining  certain  chemical 
phenomena. 

Eutectic  alloys  are  those  solid  solutions  of  one  metal 
in  another  that  have  the  lowest  melting  point.  This 
melting  point  is  lower  than  that  of  either  constituent. 
This  subject  is  of  great  importance  in  judging  the 
qualities  of  steel  under  the  microscope. 

Petrography  is  the  study  of  rocks  or  stones;  es- 
pecially applied  in  judging  their  quality  for  building 
and  other  purposes.  Polished  surfaces  are  examined 
under  magnification,  somewhat  as  is  done  on  a  section 
of  steel  and  alloys. 


316  CHEMISTRY  OF  FAMILIAR  THINGS 

Radio-activity  is  the  name  given  to  the  property  of 
certain  substances  of  giving  off  radiant  energy.  These 
radiations  ionize  1  air,  or  cause  it  to  conduct  electricity 
and  to  affect  photographic  plates,  and  make  phos- 
phorescent substances  luminous,  although  the  rays 
themselves  are  not  visible. 

Synthetic  chemistry  is  the  branch  of  chemistry  that 
deals  with  the  building  up  of  complex  substances  from 
simpler  ones,  such  as  the  making  of  dye  colors  from 
simpler  substances. 

1  Dissociates  to  the  atomic  condition. 


INDEX 


Acetylene,  49 

Acids,  11 

Adsorption  by  the  soil,  169 

Air,  65 

saltpetre,  106 
Alcohol,  193 

absolute,  241 

denatured,  241 
Ales,  236 
Alkalies,  12 

and  salts,  98 
Aluminum,  122 
Ammonium  compounds,  104 
Ampere,  47 

Analyses  of  fruits  and  nuts,  219 
Animal  feeding,  224 
Annealing,  117 
Anthrotoxins,  75 
Antidotes,  259 
Antimony,  132 
Antiseptics,  255 
Arbor  Dianae,  19 
Arsenic,  132 
Asbestos,  312 

Ash  in  organic  substances,  15 
Atoms,  9 

complexity  of,  10 

Bacteria,  89 

in  the  soil,  172 
B.  coli,  89 
B.  typhosus,  88 
Baekelite,  27 
Baking-powders,  214 
Balanced  diet,  182 
Barium,  108 
Barometer,  66 
Bases,  11 
Beer,  235 
Bismuth,  132 
Bleaching  powder,  108 
Blood,  247 


Blue  color  in  clear  sky,  32 
Borax,  112 
Brandy,  242 
Bread,  220 
Bread-making,  232 
Bromine,  111 
Butter,  203 
Buttermilk,  202 

Caffeine,  222 
Cake,  220 
Calcium,  107 

carbide,  108 
Calorimeters,  178 
Capillarity  of  soil,  167 
Carbohydrates,  182 
Carbon  dioxide  in  the  atmosphere,  67 
Carboniferous  era,  156 
Catalytic  agents,  314 
Celluloid,  280 
Cellulose,  274 
Cement,  Portland,  311 
Cements,  299 
Cerium,  132 
Cheese,  204 
Chemical  affinity,  9 
Chicken,  208 
Chlorine,  111 
Chocolate,  222 
Chondrin,  246 
Chromium,  131 
Cider,  234 
Clay,  160 
Cloth,  284 
Cocoa,  222 
Coffee,  222 

extracts,  223 
Colloid  chemistry,  315 
Colors  hi  white  light,  33 
Combustion,  74 
Composition  of  earth's  mass,  8 
Composition  of  fresh  vegetables,  217 
317 


318 


INDEX 


Conservation  in  chemistry,  64 
Cooking  of  foods,  189 
Copper,  126 
Cordials,  240 
Corpuscles,  white,  248 
Cotton,  282 

Daylight  vs.  artificial  light,  35 
Definitions,  314 
Developers,  137 
Dextrose,  231 
Diamonds,  310 
Diastase,  236 
Digestion,  179 
Dry  cells,  47 

Eggs,  198 
Electricity,  46 
Elements,  8 
Elixir  of  life,  21 
Emerald,  311 
Enzymes,  179,  314 

in  fruit,  218 
Equations,  10 
Eutectic  alloys,  315 

Fats,  182 

hydrogenation  of,  264 
Fermentation,  230 
Fertilizers,  168 
Fibres,  characteristics  of,  282 
Fireless  cookers,  84 
Fish,  197 
Flesh,  lean,  246 
Fluorine,  111 
Food  absorbed,  186 

amount  of,  requisite,  185 

energy  equivalent  of,  188 
Foods,  condimental,  222 

vegetable,  210 
Friction,  58 
Fuels,  table  of,  56 

Gas,  40 
Gasolene,  42 
Gelatin,  246 


Geologic  time,  periods  of,  155 
Gin,  242 
Glass,  307 

colors  in,  308 
Glucose,  221 
Gold,  138 

coins,  139 
Granite,  146 
Grape  juice,  237 
Gum  chicle,  299 
Gun-cotton,  280 
Gutta  percha,  299 

Haemoglobin,  248 

Hair,  247 

Hard  water,  91 

Heart,  composition  of,  etc.,  210 

Heat,  52 

Helium,  68 

Hides,  287 

Humidity,  70 

Humus,  163 

Hydrogen,  134 

dioxide,  109 
Hygrometers,  75 

latrochemistry,  21 

Ice-making,  105 

Indestructibility  of  matter,  23,  244 

Indicators,  11 

Infra-red  rays,  32 

Inorganic  chemistry,  14 

Insulation,  60 

Iodine,  111 

absorption,  269 
Iron,  115 

Kefir,  202,  243 
Keratin,  247 
Kerosene,  42 
Koumiss,  202,  243 
Kraft  paper,  278 
Krypton,  68 

Latent  heat,  22 

of  fusion,  60 

of  vaporization,  60 


INDEX 


319 


Law  of  definite  proportions,  24 

Lead,  128 

Leather,  enamel,  291 

glove,  290 

patent,  291 

suede,  291 
Lecithin,  248 
Leucocytes,  248 
Levulose,  231 
Light,  31 

chemical  influence  of,  37 

efficiencies  of,  38 

its  use  and  abuse,  44 
Lighting,  electric,  43 
Lime,  107 
Linen,  283 
Liquid  air,  72 
Lithium,  98 
Litmus  test  paper,  11 
Lobsters,  197 

Magnesium,  110 

Malt  extracts,  237 

Maltose,  231 

Manganese,  130 

Mantles,  49 

Maple  sugar,  221 

Matches,  49 

Meat,  206 

Mercury,  128 

Metals,  113 

Milk,  198 

composition  of,  183 
sanitary  production  of,  200 

Minerals,  identification  of,  306 

Molecules,  9 

Multiple  proportions,  25 

Nails,  247 
Nascent  state,  9 
Nebular  hypothesis,  143 
Neon,  68 
Nickel,  130 
Nitrates,  103 
Nitrogen,  68 

cycle  in  the  soil,  174 


Oats,  composition  of,  etc.,  211 
Oils,  drying,  268 

furniture,  271 
Oleomargarine,  204 
Olive  oil,  204 
Organic  chemistry,  14 
Orthochromatic  photography,  138 
Oxidation,  16 
Oysters,  196 
Ozone,  71,  79 

Paints,  269 

radiator,  271 
Paper,  273 

Kraft,  278 

writing,  279 
Peat,  154 
Peptase,  236 

Periodic  system  of  elements,  the,  28 
Perspiration,  247 
Petrography,  315 
Philosopher's  stone,  21 
Phlogiston,  22 
Phosphorescence,  36 
Phosphorus,  50 

Photography,  chemistry  of,  136 
Platinum,  133 
Poisons  and  antidotes,  259 
Porcelain,  309 
Porter,  236 
Potassium,  103 
Potatoes,  215 
Protein,  182 
Pure  foods,  191 
Pyroxylin,  280 

Radio-activity,  316 
Radium,  140 
Reduction,  16 

Removers,  paint  and  varnish,  271 
Respiration,  249 
Road  stones,  305 
Rock,  trap,  306 
Rocks,  302 
Rubber,  293 
hard,  296 


320 


INDEX 


Rubber,  testing  of,  298 

vulcanization  of,  295 
Rubies,  311 
Rum,  242 
Rusting  of  iron,  118 

Salt  wells,  153 
Salts,  12 
Sand,  161 
Sapphires,  311 
Sea  water,  96 
Sewage  disposal,  257 
Sheffield  plate,  134 
Shoddy,  284 
Silica,  300 
Silicon,  9,  300 
Silk,  285 

artificial,  285 
Silos,  226 
Silver,  133 

cleaning,  135 

tarnishing  of,  71 
Silvering  on  glass,  136 
Skin,  246 
Soap,  262 

laundry,  266 

powders,  266 

scouring,  267 

toilet,  265 
Soaps  as  a  class,  13 
Sodium,  98 

compounds,  100 

hydroxide,  99 
Soil  atmosphere,  167 

and  its  conservation,  158 

formation,  159 
Solvents,  267 
Specific  heat,  23,  84 
Stains,  270 

Starch,  formation  of,  in  plants,  244 
Steel  wool,  267 
Stone  for  building,  305 
Stones,  precious,  310 
Storage  battery,  48 
Strontium  compounds,  109 


Sugar,  221 

milk,  231 
Sugars,  231 
Sulphur,  111 

Sunlight,  effect  on  bacteria,  253 
Sweet  potato,  composition  of,  etc. 

215 

Symbols,  10 
Synthetic  chemistry,  316 

rubber,  294 
Syrups,  221 

Tea,  222 

Tearing-down  processes,  147 
Teeth,  249 
Tempering  steel,  117 
Thermometers,  53 
Thorium,  131 
Tin,  129 
Tongue,  210 
Topaz,  311 
Tungsten,  131 
lamp,  43 

Ultra-violet  rays,  32 
Uranium,  142 

Vacuum  cleaner,  dirt  of,  254 
Vanadium,  131 
Varnishes,  270 
spirit,  271 
Ventilation,  74 
Voltage,  47 

Water,  82 

analysis  of,  88 

purification  of,  93 
Whiskey,  240 
Wines,  237 

composition  of,  239 
Wool,  283 

Xenon,  68 

Yam,  215 
Yeast,  231 

Zinc,  124 


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